LONG-TERM OUTCOMES OF LUMBAR FUSION AMONG WORKERS' COMPENSATION SUBJECTS: AN HISTORICAL COHORT STUDY
 
   

Long-term Outcomes of Lumbar Fusion
Among Workers' Compensation Subjects:
An Historical Cohort Study

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:
   Frankp@chiro.org
 
   

FROM:   Spine (Phila Pa 1976) 2011 (Feb 15);   36 (4):   320–331

Trang H. Nguyen, MD, PhD, David C. Randolph, MD, MPH, James Talmage, MD,
Paul Succop, PhD, and Russell Travis, MD

From the Division of Epidemiology and Biostatistics,
Department of Environmental Health,
University of Cincinnati College of Medicine, Milford, OH;
Meharry Medical College, Nashville, TN; and
Department of Physical Medicine and Rehabilitation,
University of Kentucky College of Medicine, Lexington, KY.


Researchers reviewed records from 1,450 patients in the Ohio Bureau of Workers’ Compensation database who had diagnoses of disc degeneration, disc herniation or radiculopathy, a nerve condition that causes tingling and weakness of the limbs. Half of the patients had surgery to fuse two or more vertebrae in hopes of curing low back pain. The other half had no surgery, even though they had comparable diagnoses.

After two years, only 26 percent of those who had surgery had actually returned to work.
That translates to a resounding 74% failure rate!

This article also reveals that workers have a 257% better chance of returning to work IF THEY AVOID SURGERY in the first place!   That's because 67 percent of patients who had the same exact diagnosis, but DIDN'T get the surgery, DID return to work.

In another troubling finding, the researchers determined that there was a 41 percent increase in the use of painkillers, particularly opiates, in those who had the surgery. Last year we reported that deaths from addictive painkillers has doubled in the last 10 years. [6]

“The study provides clear evidence that for many patients, fusion surgeries designed to alleviate pain from degenerating discs don’t work”, says the study’s lead author Dr. Trang Nguyen, a researcher at the University of Cincinnati College of Medicine. [2]


Commentary from an MSNBC.com article titled:
“Back Surgery May Backfire on Patients in Pain”


Experts estimate that nearly 600,000 Americans opt for back operations each year. But for many like Scatena, surgery is just an empty promise, say pain management experts and some surgeons.

A new study in the journal Spine shows that in many cases surgery can even backfire, leaving patients in more pain.

Researchers reviewed records from 1,450 patients in the Ohio Bureau of Workers’ Compensation database who had diagnoses of disc degeneration, disc herniation or radiculopathy, a nerve condition that causes tingling and weakness of the limbs. Half of the patients had surgery to fuse two or more vertebrae in hopes of curing low back pain. The other half had no surgery, even though they had comparable diagnoses.

After two years, just 26 percent of those who had surgery returned to work. That’s compared to 67 percent of patients who didn’t have surgery. In what might be the most troubling study finding, researchers determined that there was a 41 percent increase in the use of painkillers, specifically opiates, in those who had surgery.

The study provides clear evidence that for many patients, fusion surgeries designed to alleviate pain from degenerating discs don’t work, says the study’s lead author Dr. Trang Nguyen, a researcher at the University of Cincinnati College of Medicine.

Unfortunately, for most patients with bad backs, there is no easy solution, no magic bullet. Pain management experts — and some surgeons — say that patients need to scale back their expectations. With the right treatments, pain can be eased, but a complete cure is unlikely.

27 million adults with back problems

A recent report by the Agency for Healthcare Research and Quality, a federal organization, found that in 2007, 27 million adults reported back problems with $30.3 billion spent on treatments to ease the pain. While some of that money is spent on physical therapy, pain management, chiropractor visits, and other non invasive therapies, the biggest chunk pays for spine surgeries.


Commentary from:
Mark Russi
Yale University School of Medicine,
New Haven, CT, USA.

This article is noteworthy as an examination of outcomes among patients with work-related low back injuries who have undergone fusion surgery. While it is a retrospective study and adequate comparability between the surgically treated group and the non-surgically treated group cannot be guaranteed, outcomes among those undergoing fusion surgery revealed an alarming number of poor clinical outcomes.

The authors compared 725 lumbar fusion cases with 725 controls. All study subjects were drawn from a Workers? Compensation database. At 2 years, only 26% of individuals who underwent fusion surgery had returned to work, compared to 67% of those not treated surgically. Of those undergoing fusion surgery, 36% suffered surgical complications and 27% required additional surgery.

The rates of permanent disability were 11% among those who underwent fusions and 2% among those who did not undergo surgery. Over the course of the study, 17 surgical patients died, compared to 11 controls. While the baseline characteristics of surgical and non-surgical patients were examined, including diagnosis, weekly wages, legal representation, total days off, magnetic resonance imaging (MRI) findings, number of vocational and rehabilitation sessions, body mass index (BMI), daily opioid dose and discogram performance -- and no statistically important interactions were found -- it is still not possible to guarantee that the fusion and control populations were truly equivalent with respect to severity of lumbar disc disease.

That said, even with absent comparison with a non-surgical group, the outcomes among those undergoing fusion were alarming. An implication of this study would include the need to examine in a prospective way outcomes among clinically comparable patients randomized to fusion surgery or conservative therapy.

On a practical clinical level, the study suggests that patients contemplating lumbar fusion surgery need to be educated regarding the sub-optimal outcomes associated with the procedure. Patients contemplating lumbar fusion surgery should be informed regarding the outcomes associated with the procedure, including the low likelihood of returning to work, high rate of reoperation, high rate of complications and the possibility of permanent disability.



The Abstract:

STUDY DESIGN:   Historical cohort study.

OBJECTIVE:   To determine objective outcomes of return to work (RTW), permanent disability, postsurgical complications, opiate utilization, and reoperation status for chronic low back pain subjects with lumbar fusion. Similarly, RTW status, permanent disability, and opiate utilization were also measured for nonsurgical controls.

SUMMARY OF BACKGROUND DATA:   A historical cohort study of workers' compensation (WC) subjects with lumbar arthrodesis and randomly selected controls to evaluate multiple objective outcomes has not been previously published.

METHODS:   A total of 725 lumbar fusion cases were compared to 725 controls who were randomly selected from a pool of WC subjects with chronic low back pain diagnoses with dates of injury between January 1, 1999 and December 31, 2001. The study ended on January 31, 2006. Main outcomes were reported as RTW status 2 years after the date of injury (for controls) or 2 years after date of surgery (for cases). Disability, reoperations, complications, opioid usage, and deaths were also determined.

RESULTS:   Two years after fusion surgery, 26% (n = 188) of fusion cases had RTW, while 67% (n = 483) of nonsurgical controls had RTW (P= 0.001) within 2 years from the date of injury. The reoperation rate was 27% (n = 194) for surgical patients. Of the lumbar fusion subjects, 36% (n = 264) had complications. Permanent disability rates were 11% (n = 82) for cases and 2% (n = 11) for nonoperative controls (P= 0.001). Seventeen surgical patients and 11 controls died by the end of the study (P = 0.26). For lumbar fusion subjects, daily opioid use increased 41% after surgery, with 76% (n = 550) of cases continuing opioid use after surgery. Total number of days off work was more prolonged for cases compared to controls, 1140 and 316 days, respectively (P < 0.001). Final multivariate, logistic regression analysis indicated the number of days off before surgery odds ratio [OR], 0.94 (95% confidence interval [CI], 0.92–0.97); legal representation OR, 3.43 (95% CI, 1.58–7.41); daily morphine usage OR, 0.83 (95% CI, 0.71–0.98); reoperation OR, 0.42 (95% CI, 0.26–0.69); and complications OR, 0.25 (95% CI, 0.07–0.90), are significant predictors of RTW for lumbar fusion patients.

CONCLUSIONS:   This Lumbar fusion for the diagnoses of disc degeneration, disc herniation, and/or radiculopathy in a WC setting is associated with significant increase in disability, opiate use, prolonged work loss, and poor RTW status.



From the FULL TEXT Article:

Background

Lumbar arthrodesis (fusion) is a surgical procedure performed to unite spinal vertebrae to eliminate mobility. There have been few published studies evaluating lumbar fusion outcomes in US workers’ compensation subjects. [1–4] In these studies, reoperation rates are the only outcome that has been consistently reported (about 22%). Surgical complications of 12% were reported in only one study at 3 months after surgery. [1] Permanent or temporary disability results 2 years after fusion are variable among the studies, 18% to 68%. [1, 2, 4] Similarly, return to work status (RTW) also varied from 41% to 78%. [2, 4]

True outcomes are difficult to determine when results are variable. The number of lumbar fusions for degenerative conditions has increased 220% in the United States from 1990. [5] A recent systematic review of randomized clinical trials comparing lumbar fusion to conservative care indicates solid conclusions cannot be reached due to the methodologic limitations and limited data. [6] In 2006, a different systematic review questioned the cost effectiveness of lumbar fusion. [7] In this study, OH Workers’ Compensation data from January 1, 1999 to January 31, 2006 was used to assess the work status 2 years after lumbar fusion, permanent disability awards, surgical complications, reoperation status, and pain medication usage among cases and randomly selected controls with chronic low back pain (CLBP).



MATERIALS AND METHODS

Data for this historical cohort study were collected from the Ohio Bureau of Workers’ Compensation database. Extracted data included information on the injury (accident information and occupation), demographics, procedures, office visits, medications, RTW, permanent disability, and death. Personal identification information was not a part of the data.

      Study Population

After approval by the Institutional Review Board at the University of Cincinnati College Of Medicine, 1450 study subjects were identified from the Ohio Bureau of Workers’ Compensation database. Cases were subjects 18 to 70 years of age with CLBP classified by International Classification of Diseases, Ninth Revision, Clinical Modification diagnoses and Current Procedural Terminology codes for lumbar arthrodesis (Tables 1, 2). [8, 8]

The database had 3138 workers with lumbar fusion and dates of injury between January 1, 1999 and December 31, 2001. “Date of injury” is the date on which a work-related injury occurred. Subjects with lumbar fusion after the cutoff date of July 31, 2003, and/or having injuries to other body parts in addition to the lumbar spine were excluded. A total of 725 lumbar fusion cases were eligible for the study. There were 10,518 nonoperated, CLBP subjects with similar injury dates and low back pain International Classification of Diseases, Ninth Revision, Clinical Modification diagnoses (Table 1). Subjects with spinal fracture, involvement of other body parts, cervical and/or thoracic areas, head trauma, or pregnancy were excluded. After exclusion due to involvement of other body parts and controlling for age, gender, and diagnoses, 3587 eligible controls remained. From this pool, 725 controls were selected randomly by computer (Figure 1).

This study design did not require direct contact with study subjects. The lost to follow-up rate was 1.4% due to lack of RTW status of 21 subjects (7 cases and 14 controls). Follow-up mean duration was 4.78 years for cases and 3.46 years for controls. The study ended on January 31, 2006.


Table 1.   ICD-9 CM Diagnoses
for Low Back



Table 2.   Instructions to
Categorize the Types of
Lumbar Fusion


Figure 1.   Subjects selection for
lumbar arthrodesis— Historical
Cohort Study.




      Primary and Secondary Outcomes Measured

The primary outcome was RTW status. The secondary outcomes were permanent disability award, complications, reoperations, and opiate utilization.

RTW was considered successful if the injured worker returned to employment 2 years after the date of surgery for cases or 2 years after injury for controls as part-time, full-time work ers with the same or a different employer. Unsuccessful RTW was defined as failure to RTW in any capacity. Disability status was defined as workers who were awarded permanent total disability status after surgery or after injury. Permanent total disability is permanent lifetime compensation.

Complications were classified as early major systemic (<6 weeks postoperative), neurologic, implant, late spinal, or wound complications. [10]

Reoperation was defined as repeat lumbar surgical procedure(s) performed during the follow-up period. These repeat surgical procedures included the following: fusions, removal and/or insertion of fixation device(s), laminectomy, bone grafts, explora tion, and decompression of the lumbar spine. [11, 12]

Opioid utilization was limited to the oral route. For each oral narcotic analgesic, the date, name, dose, and quantity dispensed were converted to morphine equivalent units (MEQ). Cumulative dose per day was calculated. Average amount of opioids before surgery, after surgery, and during the entire length of the study were determined. [13] Mortality status was categorized as perioperative mortality (i.e., within 6 weeks postoperative) and long-term mortality from any cause. [14, 15]

      Statistical Analysis

RTW rates among lumbar fusion subjects have been reported as 41% to 78%. [2, 4] A sample size of 250 cases and 250 controls provided an alpha (2–sided) of 0.05 (Type I error) and beta value of 0.14 (Type II error). This sample size provided 86% power to detect a 10% difference between the surgical fusion cases and nonsurgical controls. This was a conservative estimate of the case-control difference. [16]

Baseline characteristics of the cohorts were compared using χ2 tests, frequencies, and percentages for categorical variables. T tests, means, and standard deviations were reported for continuous variables. Independent variables included age, gender, diagnoses, smoking history, weekly wages, legal representation, marital status, education, total days off, number of days from the date of injury to date of surgery, number of reoperations, complications, lumbar magnetic resonance imaging (MRI) findings, number of vocational and rehabilitation sessions, body mass index (BMI), daily opioid dose, fusion approaches, and discogram performance. The above covariates were included in the regression models because they have been reported in the literature to affect the outcomes of interest. [17–27] Stepwise logistic regression (LR) was performed to determine the magnitude of association of the independent variables in predicting RTW. Unadjusted and adjusted odds ratios (OR) are presented with 95% confidence intervals (CIs). No statically important interactions were found. The final multivariate models were determined based on clinically meaningful and statistically significant predictors, high concordance indexes, and the Hosmer and Lemeshow Goodness of Fit test.

All analyses were performed using SAS software, version 9.1. Two-sided P values and 95% CIs are reported; P < 0.05 is considered to be statistically significant.



RESULTS

Demographics of all subjects are presented in Table 3. Legal representation, current smokers, and female gender were more common in the surgical cases than in the controls. Sex was not a statistically significant predictor of RTW status in unadjusted or adjusted LR analyses. Smoking status was better documented for cases than controls secondary to cases having longer care and thus more office visits. Cases had more legal representation. Cases also had higher average preinjury weekly wages compared to controls. Age, BMI, education, and marital status were not statistically significant between the 2 groups. Approximately 72% of the diagnoses for all subjects were disc degeneration and disc herniation. About 80% of cases and 70% of controls had 1 or 2 levels of degenerative disc changes on MRI (Table 3). Lumbar MRI findings and diagnoses were not statistically significant predictors of the adjusted RTW status.

After considering subjects who were dead (17 cases, 11 controls), permanently disabled (82 cases, 11 controls) or in rehabilitation at 2 years (64 cases, 43 controls), the actual RTW status at 2 years was 26% (n = 188) of cases and 67% (n = 483) of controls. Surgical cases remained off work longer than controls 1140 days versus 316 days, respectively (P < 0.001). The average duration from the date of injury to the date of surgery was 597 days. This duration was not significant in the RTW adjusted analysis (Table 4).

There were 264 cases (36%) with surgical complications. Frequencies and definitions of complications are provided in Table 5. Complication frequency was high because of the inclusion of late spinal complications. This group made up 25% of all complications. Most late spinal complications consisted of post laminectomy syndrome and adjacent segment degeneration. The ranges of wound, im plant, neurologic, and early complications were 2% to 6%. Of the surgical subjects, 64% had no complications.

Lumbar reoperations occurred in 27% of the cases (n = 194). About 66% (n = 160) of the reoperations occurred within 2 years of the index surgery. A large number of reoperations consisted of removal of instrumentation, re-exploration, and additional arthrodesis (Table 5). Complications and reoperations will be further investigated in subsequent article.


Table 3.   Baseline Characteristics
of Lumbar Fusion Cases and
Nonsurgical Controls


Table 4.   Return to Work,
Rehabilitation, Disabled,
and Death Status


Table 5.   Reoperations After
Index Surgery





Throughout the entire study, 85% (n = 614) of the lumbar fusion cases were using opioids compared to 49% (n = 354) of controls. The average daily MEQ increased from 44.23 ± 33.57 U before surgery to 62.31 ± 70.80 U after surgery. There is a 41% increase in the mean daily opioid dosage postoperatively. The average daily, postsurgery MEQ reported is the amount of opioid taken more than 90 days postoperatively (Table 5). In both the univariate (P < 0.001) and the multivariate (P = 0.03) LR analysis, the daily MEQ was a significant negative predictor of fusion cases having successful RTW (Tables 6, 7).

Unadjusted LR indicated a number of factors were significant negative predictors of RTW status at 2 years postfusion (Table 6). Complications as a group affected RTW status significantly (P < 0.001). More specifically, RTW chances were early major systemic complications OR, 0.22 (95% CI, 0.08–0.64; P = 0.005); implant complications OR, 0.07 (95% CI, 0.009– 0.53; P = 0.01); late spinal complications OR, 0.49 (95% CI, 0.31–0.77; P = 0.002); and neurologic complications OR, 0.42 (95% CI, 0.09–2.06; P = 0.29). Neurologic and wound complications were not statistically significant (Table 6). This finding persisted in the adjusted LR analysis (Table 7).


Table 6A.   Univariate Logistic
Regression of Return
to Work Status


Table 6B.  



Table 7.   Final Multivariate Logistic
Regression Models of Return
to Work Status




Subjects who had reoperations once after the index fusion had a RTW OR, 0.28 (95% CI, 0.17–0.48;P < 0.001) compared to subjects with no reoperation (Table 6).

The total number of days off work was a highly significant negative predictor of RTW in fusion cases and in nonoperated controls, in both adjusted and unadjusted F2 models (Figure 2). At 30 days of work absence, the unadjusted OR for RTW in fusion cases was 0.93 (95% CI, 0.92–0.94; P ≤ 0.001) and for nonoperated controls was 0.85 (95% CI, 0.82–0.88; P ≤ 0.001) (Table 6).

Weekly wages was a strong predictor of RTW status for all subjects. The higher the preinjury weekly wages, the F3 more likely the individual was to RTW (Figure 3). A subject earning $100.00 more per week had an increased odds of RTW (OR, 1.09; 95% CI, 1.01–1.18; P < 0.02) (Table 7).


Figure 2.   Total days off work as predictor
of return to work status.


Figure 3.   Weekly wages as predictor
of return to work status.




Both current smoking and legal representation were significant negative predictors of RTW in univariate and multivariate analyses. Cases without legal representation were 3 times more likely to RTW OR 3.43 (95% CI, 1.58–7.41; P < 0.002) (Table 7).

The more rehabilitation sessions (therapy) provided, the less likely cases and controls were to RTW. At 10 therapy sessions, the RTW OR was 0.92 (95% CI, 0.87–0.97; P ≤ 0.001) for fusion cases and 0.95 (95% CI, 0.93–0.98, P < 0.001) for controls. With 20 therapy sessions, the RTW OR was 0.85 (95% CI, 0.76–0.94; P = 0.002) for cases and 0.91 (95% CI, 0.86–0.96; P < 0.001) for controls (Table 6). Rehabilitation and vocational sessions were not statistically significant predictors of RTW in the final adjusted analysis.

Age, BMI, diagnoses, education, surgical fusion approach, sex, marital status, the number of lumbar levels with degenerative changes, and the number of vocational sessions were not significant predictors of RTW in either adjusted or unadjusted analysis.

The final adjusted LR model indicated current smoking, the number of total days off work, and weekly wages were significant predictors of RTW status with OR, 0.65 (95% CI, 0.42–1.01; P = 0.05); OR, 0.93 (95% CI, 0.92–0.94; P ≤ 0.001); and OR, 1.09 (95% CI, 1.01–1.18; P = 0.02) for the entire cohort, respectively (Table 7).

Multivariate analysis of only fusion cases showed the complications OR, 0.25 (95% CI, 0.07–0.90; P = 0.03); reoperation status OR, 0.42 (95% CI, 0.26– 0.69; P ≤ 0.001); total days off before surgery OR, 0.94 (95% CI, 0.92–0.97; P < 0.001); legal representation OR, 3.43 (95% CI, 1.58–7.41; P = 0.002); and total daily MEQ OR, 0.83 (95% CI, 0.71–0.98; P = 0.03) as significant negative predictors of RTW, while higher average weekly wages remained a predictor of increase chances of RTW OR, 1.12 (95% CI, 1.03–1.21; P = 0.008) (Table 7).

Similar to surgical patients, age, BMI, diagnosis, education, sex, marital status, MRI findings, and vocational training were not significant predictors of RTW status in both unadjusted and adjusted LR analysis for nonsurgical controls. Legal representation, current smoking, and total rehab sessions were significant predictor of RTW status in only unadjusted analysis. These effects did not persist in the adjusted analysis for controls (Table 6).

Nonsurgical controls adjusted LR model showed only the total number of days off, and weekly wages were significant predictors of RTW. The longer the duration off work the less likely a subject was to RTW with an OR, 0.85 (95% CI, 0.82–0.88; P < 0.001). Weekly wages continued to show the same trend as cases. Higher wages increased the odds of RTW OR 1.16 (95% CI, 1.02–1.32; P = 0.02).



DISCUSSION

Lumbar fusion is a controversial operation for degenerative disc disease and herniated disc. [5, 6] It is most commonly performed in the United States for the diagnosis of degenerative disc disease. [5, 28] A large population study of workers’ compensation lumbar fusion subjects with multiple objective outcomes and randomly selected controls has not been published.

In this study, we evaluated RTW, disability, complications, reoperations, and opioid usage among cases and randomized controls. RTW is an important objective personal health outcome, as multiple studies have shown that being out of work is associated with poor health. Employment not only provides needed income, it is a part of the individual’s self image and socioeconomic status. Being out of work or being disabled from work also has an important societal impact. Unemployment has been associated with cardiovascular disease, cancer, suicide, poverty, increase of spousal and child abuse, domestic violence, divorce, and higher utilization of healthcare services. [29–35] RTW is, and should be, an objective end point for treatment provided in a workers’ compensation setting.

This study showed surgical fusion cases were more likely to be permanently disabled (n = 82 vs. n = 11, P = 0.001) and more likely to not RTW than the nonsurgical controls (n = 367 vs. n = 163, P < 0.001). Combining the permanently disabled with surgical cases who failed to RTW, yielded a 62% disability status (n = 449). This result is consistent with the disability status reported from the Washington state workers’ compensation data base as 68% in 1994 [4] and 64% in 2006. [1]

The average age for all subjects in the study was 39 years old, and these were healthy working individuals at the time of injury. The complications was high compared to Maghout-Juratli et al study [1] secondary to including long-term “late” spinal and neurologic complications. Adjacent segment degeneration and post laminectomy syndrome made up to 72% of the late spinal complications. Most lumbar surgical studies include only short-term complications (i.e., within 6 weeks after fusion). As a result, late spinal complications are seldom reported. Without the late spinal and neurologic complications, our complications rate of 15% (early major systemic, implant and wound complications) is comparable to Maghout-Juratli’s short-term complication rate of 12% (Table 5).

Reoperation rates have been reported consistently by Utah and Washington states in the past, 20% and 22%, respectively. [2, 1, 4] Utah’s reoperation rate was self reported. Both Washington studies reported reoperation rates within 2 years of the index surgery. [1, 4] The reoperation rate was slightly higher (27%) in this study because reoperation was tracked until the end of the study. However, the reoperation rate was 22% if the reoperation was only considered within 2 years of the index surgery.

Lumbar spine fusion does not seem to be an effective operation for the workers’ compensation subjects with the diagnoses of disc degeneration, disc herniation, and/or radiculopathy. Our data indicate 84% of the diagnoses for the surgical patients were disc degeneration, disc herniation, and radiculopathy (Table 3). These diagnoses remain controversial indications for lumbar fusion, while subjects with spondylolisthesis with instability, traumatic fractures, or tumor have had good results. Lumbar arthrodesis should be cautiously considered and recommended only in workers’ compensation subjects with clear cut indications.

The best lumbar arthrodesis approach (posterior, anterior, or combined), technique (noninstrumented, instrumented, etc.), and single or multi-levels remain debatable in the spine literature. Our analyses indicated the type of surgery performed was not a statistically significant predictor of RTW status (Table 6).

It is important to note that 5 of the 8 factors that remained statistically significant in the final multivariate analysis are psychosocial variables including current smoking status, total days off, the number of days off before surgery, weekly wages, and legal representation (Table 7). [36–40]

The only clinical findings that remained significant in predicting RTW status were complications, reoperations, and daily MEQ. Similar to other studies, clinical factors of preoperative diagnoses, lumbar MRI findings, fusion types, the number of rehabilitation, or vocational sessions were not statistically significant and did not appear to be associated with RTW status. [1, 2]

Total number of days off was the most important predictor of RTW status irrespective of surgical or nonsurgical treatment. This variable is distinct from another variable that measured the duration from the date of injury to the date of surgery; the latter was not statistically significant.

Thus, time off work (or time off work before surgery) and not time from injury to surgery was the predictive variable. The number of days off work remained highly significant in unadjusted and adjusted analyses of cases only, controls only, and the entire cohort. At 2 years off work, the odds that fusion cases would RTW were 0.16 (95% CI, 0.12 0.22; P ≤ 0.001). This effect appears to be even more important in controls. Controls’ odds of RTW were 0.02 (95% CI, 0.009– 0.05; P ≤ 0.001) (Figure 2). Controls with prolonged days off work had much smaller chances of RTW compared to cases. It should be noted that none of the medical factors were statistically significant predictors of RTW status in the final adjusted model for controls (Table 7).

Similarly, the number of days remaining off work before surgery was a significant predictor of RTW status. The longer the duration the subject remain off work before surgery, the less likely the chances of RTW success fully. At 90 days off work before surgery, the odds of RTW were 0.83 (Table 7).

At least 76% (n = 550) of the fusion cases were still taking opioids more than 90 days after surgery with average daily MEQ increased by 41%. The daily MEQ reported reflect an underestimate of the opioid dose because only oral opioids with reliable conversion to morphine were used to calculate daily total MEQ. Nasal sprays, transdermal, and parenteral routes of opioid administration were not included in this study. This outcome questions lumbar fusion effectiveness in relieving low back pain and the validity of the self-reported pain scores and functional questionnaires that have been used for years as a part of the measurement of the effectiveness of low back pain interventions. Figure 4 shows the ORs between opioid dose and RTW. This graph demonstrates the profound association of opioid use on RTW status with far greater impact on cases, as opposed to controls. The greater the daily total amount of opioids, the less likely it was for a worker to RTW. The odds of RTW dropped sharply with small increases in the dose of opioids. At 100 MEQ units, the OR of RTW for cases was 0.25 (95% CI, 0.14–0.46; P < 0.001) compared to the controls’ OR of 0.93 (95% CI, 0.68–1.28, P < 0.65). Many other studies published previously have also suggested long-term opioid therapy for noncancer pain may not be in a patient’s best interest. [41–46] Continued usage of opioids in the workers’ compensation system without long-term randomized trials and/or large population studies is not recommended in light of these findings.


Figure 4.   Total morphine equivalents
as predictor of return to work ststus.





The association of wages and RTW status is seldom addressed in the medical literature. In this study, weekly wages was a significant predictor of RTW status in both univariate and multivariate LR analysis for all subjects (Tables 6, 7).

The higher the weekly wages, the more likely an injured worker was to RTW. Patients with higher incomes may have more incentive to RTW, or may have more employment options, as higher wages often suggests more marketable job skills.

Finally, similar to previous studies, this study showed that legal representation was a strong negative predictor of RTW in both cases (OR, 3.98; 95% CI, 2.17–7.30; P < 0.001) and nonsurgical controls (OR, 5.83; 95% CI, 3.14–10.83; P < 0.001). [1, 2, 47]

This study has several limitations. Not all risk factors that may affect the surgical outcomes are documented consistently in the database (i.e., smoking history). Although numerous independent factors have been collected, it is possible that there are other significant but unconsidered factors. An historical cohort study design is not the best method to evaluate the effectiveness of surgical intervention. However, this study has many advantages. The study design permits a prolonged follow-up in a very large cohort with multiple objective outcomes measured. Using objective outcomes eliminates difficulties associated with self-reported questionnaires of pain and function. Data are collected from medical providers throughout the state of Ohio, and unlikely to be affected by referral pattern bias.

Our results are very similar to Washington state studies. [1, 4] Randomized controlled trials specifically for workers’ compensation subjects with lumbar fusion should be performed.

In summary, this large historical cohort study suggests that lumbar fusion may not be an effective operation in workers’ compensation patients with the diagnoses of disc degeneration, disc herniation, and/or radiculopathy. This procedure is offered to improve pain and function, yet objective outcomes showed increased permanent disability, poor RTW status, and higher doses of opioids. The combination of lumbar fusion surgery for disc degeneration, disc herniation and/or radiculopathy, opiates, prolonged work absence, and legal representation appear to create a diminished quality of life for the injured workers under these circumstances. Additional studies are currently underway to further investigate these factors.


Key Points

  • Workers’ compensation subjects with lumbar arthrodesis had a poor RTW status 2 years after surgery, higher disability status, and a larger number of subjects continued on daily opioids compared to nonsurgical controls. significant predictors of RTW status for surgical cases were the number of days off, legal representation, weekly wages, complications, reoperations, and total morphine usage. Number of days off and weekly wages were the only significant predictors of RTW status for nonsurgical controls.

  • Legal representation decreased the odds of the injured worker returning to work.

  • The use of opiates decreased the odds of RTW significantly for surgical subjects.

  • Control subjects with prolonged work absence have poorer odds of RTW compared to surgical cases.



Acknowledgments

The authors thank K. Nguyen, D. Hubbard, and C. Krabacher for administrative, technical, or material support.



References:

  1. Magh out-Juratli S, Franklin GM, Mirza SK, et al.
    Lumbar fusion outcomes in Washington state workers’ compensation.
    Spine 2006;31:2715–23.

  2. DeBerard MS, Colledge AL, Masters KS, et al.
    Outcomes of posterolateral versus BAK titanium cage interbody lumbar fusion in injured workers: a retrospective cohort study.
    J South Orthop Assoc 2002;11:157–66.

  3. Hodges SD, Humphreys SC, Eck JC, et al.
    Predicting factors of successful recovery from lumbar spine surgery among workers’ compensation patients.
    J Am Osteopath Assoc 2001;101:78–83.

  4. Franklin GM, Haug J, Heyer NJ, et al.
    Outcome of lumbar fusion in washington state workers’ compensation.
    Spine 1994;19:1897–903; discussion 1904.

  5. Deyo RA, Gray DT, Kreuter W, et al.
    United States trends in lumbar fusion surgery for degenerative conditions.
    Spine 2005;30:1441–5.

  6. Mirza SK, Deyo RA.
    Systematic review of randomized trials comparing lumbar fusion surgery to nonoperative care for treatment of chronic back pain.
    Spine 2007;32:816–23.

  7. Soegaard R, Christensen FB.
    Health economic evaluation in lumbar spinal fusion: a systematic literature review anno 2005.
    Eur Spine J 2006; 15:1165–73.

  8. Practice Management Information Corporation.
    International Classification of Diseases-9th Revision, Clinical Modification. 9th ed.
    Los Angeles, CA: Practice Management Information Corporation; 2004.

  9. American Medical Association.
    Current Procedural Terminology 2004: Professional Edition.
    Chicago, IL: American Medical Association Press, 2003.

  10. Schwender JD, Casnellie MT, Perra JH, et al.
    Perioperative complications in revision anterior lumbar spine surgery: incidence and risk factors.
    Spine 2009;34:87–90.

  11. Malter AD, McNeney B, Loeser JD, et al.
    5-year reoperation rates after different types of lumbar spine surgery.
    Spine 1998;23:814–20.

  12. Deyo RA, Ciol MA, Cherkin DC, et al.
    Lumbar spinal fusion. A cohort study of complications, reoperations, and resource use in the Medicare population.
    Spine 1993;18:1463–70.

  13. Interagency Guideline on Opioid Dosing for Chronic Non-Cancer Pain:
    An Educational Pilot to Improve Care and Safety With Opioid Treatment.
    Olympia, WA: Washington State Department of Labor and Industries; 2007. Available at:
    http://www.agencymeddirectors.wa.gov/Files/2006FAQV8.pdf
    Accessed April 25, 2009.

  14. Deyo RA, Cherkin DC, Loeser JD, et al.
    Morbidity and mortality in associ ation with operations on the lumbar spine: the infl uence of age, diagnosis, and procedure.
    J Bone Joint Surg Am 1992;74:536–43.

  15. Juratli SM, Mirza SK, Fulton-Kehoe D, et al.
    Mortality after lumbar fusion surgery.
    Spine 2009;34:740–7.

  16. Hulley S, Cummings S, Browner W.
    Designing Clinical Research. 2nd ed.
    Philadelphia, PA: Lippincott Williams & Wilkins; 2001.

  17. Frank JW, Kerr MS, Brooker AS, et al.
    Disability resulting from occupational low back pain. Part I: what do we know about primary prevention? A review of the scientifi c evidence on prevention before disability begins.
    Spine 1996;21: 2908–17.

  18. Frymoyer JW.
    Predicting disability from low back pain.
    Clin Orthop Relat Res 1992:101–9.

  19. Frymoyer JW, Rosen JC, Clements J, et al.
    Psychologic factors in low-back pain disability.
    Clin Orthop Relat Res 1985:178–84.

  20. Gatchel RJ, Polatin PB, Mayer TG.
    The dominant role of psychosocial risk factors in the development of chronic low back pain disability.
    Spine 1995; 20:2702–9.

  21. Gatchel RJ, Mayer TG, Kidner CL, et al.
    Are gender, marital status or parenthood risk factors for outcome of treatment for chronic disabling spinal disorders?
    J Occup Rehabil 2005;15: 191–201.

  22. Glassman SD, Alegre G, Carreon L, et al.
    Perioperative complications of lumbar instrumentation and fusion in patients with diabetes mellitus.
    Spine J 2003;3:496–501.

  23. Proctor T, Gatchel RJ, Robinson RC.
    Psychosocial factors and risk of pain and disability.
    Occup Med 2000;15:803–12.

  24. Robinson RC, Gatchel RJ, Polatin P, et al.
    Screening for problematic prescription opioid use.
    Clin J Pain 2001;17:220–8.

  25. Sandhu H, Zdeblick T, Foley K.
    Spinal fusion and smoking: is pseudarthrosis the cause for poorer clinical outcome?
    Spine J 2002;2(suppl):82S.

  26. Ahn N, Ahn U, Post Z.
    Smoking, diabetes and excessive preoperative epidural steroid administration are risk factors for intraoperative dural tears.
    Spine J 2004;4(suppl):22S.

  27. Vaidya R, Carp J, Bartol S, et al.
    Lumbar spine fusion in obese and morbidly obese patients.
    Spine 2009;34:495–500.

  28. Lee CK, Langrana NA.
    A review of spinal fusion for degenerative disc disease: need for alternative treatment approach of disc arthroplasty?
    Spine J 2004;4:173S–6S.

  29. Waddell GA, Burton AK.
    Is Work Good for Your Health and Well Being?
    London, United Kingdom: The Stationery Office; 2006.

  30. Platt S.
    Unemployment and suicidal behaviour: a review of the literature.
    Soc Sci Med 1984;19:93–115.

  31. Pritchard C.
    Is there a link between suicide in young men and unemployment?
    A comparison of the UK with other European community countries.
    Br J Psychiatry 1992;160:750–6.

  32. Dooley D, Fielding J, Levi L.
    Health and unemployment.
    Annu Rev Public Health 1996;17:449–65.

  33. Jin RL, Shah CP, Svoboda TJ.
    The impact of unemployment on health: a review of the evidence.
    CMAJ 1995;153:529–40.

  34. Mathers CD, Schofield DJ.
    The health consequences of unemployment: the evidence.
    Med J Aust 1998;168:178–82.

  35. Lynge E.
    Unemployment and cancer: a literature review.
    IARC Sci Publ 1997:343–51.

  36. Boos N, Semmer N, Elfering A, et al.
    Natural history of individuals with asymptomatic disc abnormalities in magnetic resonance imaging: predictors of low back pain-related medical consultation and work incapacity.
    Spine 2000;25:1484–92.

  37. Burton AK, Tillotson KM, Main CJ, et al.
    Psychosocial predictors of out come in acute and subchronic low back trouble.
    Spine 1995;20:722–8.

  38. Hurwitz EL, Morgenstern H, Yu F.
    Cross-sectional and Longitudinal Associations of Low-back Pain and Related Disability with Psychological Distress Among Patients Enrolled in the UCLA Low-Back Pain Study
    J Clin Epidemiol. 2003 (May); 56 (5): 463–471

  39. Carragee EJ.
    Psychological and functional profi les in select subjects with low back pain.
    Spine J 2001;1:198–204.

  40. Carragee EJ.
    Psychological screening in the surgical treatment of lumbar disc herniation.
    Clin J Pain 2001;17:215–9.

  41. Juratli SM, Mirza SK, Fulton-Kehoe D, et al.
    Mortality after lumbar fusion surgery.
    Spine 2009;34:740–7.

  42. Kidner CL, Mayer TG, Gatchel RJ.
    Higher opioid doses predict poorer functional outcome in patients with chronic disabling occupational musculoskeletal disorders.
    J Bone Joint Surg Am 2009;91:919–27.

  43. Dersh J, Mayer TG, Gatchel RJ, et al.
    Prescription opioid dependence is associated with poorer outcomes in disabling spinal disorders.
    Spine 2008; 33:2219–27.

  44. Franklin GM, Mai J, Wickizer T, et al.
    Opioid dosing trends and mortality in Washington state workers’compensation, 1996–2002.
    Am J Ind Med 2005; 48:91–9.

  45. Webster BS, Verma SK, Gatchel RJ.
    Relationship between early opioid prescribing for acute occupational low back pain and disability duration, medical costs, subsequent surgery, and late opioid use.
    Spine 2007;32: 2127–32.

  46. Eriksen J, Sjøgren P, Bruera E, et al.
    Critical issues on opioids in chronic non-cancer pain: an epidemiological study.
    Pain 2006;125:172–9.

  47. Harris I, Mulford J, Solomon M, et al.
    Association between compensation status and outcome after surgery: a meta-analysis.
    JAMA 2005;293: 1644–52.



Return to the LOW BACK PAIN Section

Since 10–23–2010

         © 1995–2018 ~ The Chiropractic Resource Organization ~ All Rights Reserved