Chiropractic care for hypertension: Review of the literature and study of biological and genetic bases

doi:10.23750/abm.v91i13-S.10524

Table S1.

Brief description of research studies investigating the effects of chiropractic therapy on hypertension

First author, year Participants Study design Control group Type of CMT Results Limitations
Bakris et al 200788 50 patients with stage 1 hypertension subdivided in treated (25) and controls (25) Double blind, placebo controlled. Duration: 8
weeks Treatment vs placebo Atlas/Upper cervical chiropractic adjustment Systolic BP (treatment: -17+/-9 mmHg vs placebo: -3+/-11 mmHg, P<0.0001)
Diastolic BP (treatment: -10+/-11 mmHg vs placebo: -2+/-7 mmHg, P=0.002).
No adverse effects recorded Should be confirmed in a larger trial

Toms 201290 42 patients subdived in 3 groups: 12 hypotensive, 12 nomiotensive, 18 prehypertensive or stage 1 or stage 2 hypertensive Cohort study. Duration: 1 treatment Pre-treatment vs posttreatment Atlas orthogonal upper cervical adjustment Hypotensive group: systolic BP (+13.83mmHg, p<0.0001); diastolic BP (+8.83, p=0.0003). Nomiotensive group: systolic BP (- 3.92, p= 0.1107); diastolic BP (-1.58, p=0.2486).
Pre-hypertensive + hypertensive groups: systolic BP(-20.22mmHg, p<0.0001); diastolic BP (-6.83mmHg, p<0.0001). No adverse effects recorded. Absence of a specific control group. Follow-up measurements did not measure the duration of the effects

Toms 201491 20 participants ( 10 placebo group, 10 therapeutic group) Placebo-controlled, randomized, prospective longitudinal cohort study. Duration:
6 weeks Controls vs treatment Atlas orthogonal upper cervical chiropractic care Systolic BP (-12.2mmHg, p<0.05); Diastolic BP (-7.2; p<0.05) The effect on the diastolic values were not significant after 4 weeks

Ward et al 201292 48 nomiotensive college students (24 controls, 24 treated) Single blind, randomized controlled trial. Duration: 24h Controls vs treatment Atlas cervical break No significant differences before and after chiropractic care compared to head turn and no contact control Non-hypertensive patients

Knutson 200194 110 patients (80 in test one, 30 in test two) Comparison study Test 1: controlled clinical trial with a treatment group and a control group. Test 2: controlled clinical trial with subjects as controls Vectored upper cervical care Test 1: Significant decrease in systolic blood pressure (p<0.001); Test 2: No significant decrease in systolic blood pressure Lack of randomization, blinding, manipulated control group

Kessinger et al 201995 130 patients subdivided in 3 groups: 54 with low pulse pressure (<40mmHg), 29 with medium pulse pressure (40 49mmHg), 47 with high pulse pressure (>49 mmHg) Observational comparison study Pre-treatment vs posttreatment Knee chest upper cervical Pulse pressure (-8.9mmHg, p<0.01) in patients with hypertension Lack of randomization, not a clinical trial

Plaugher et al 200297 Subdivided in 3 groups: 9 undertook chiropractic, 8 a brief massage, 6 untreated. Study duration: 2 months comparison trial with 3 parallel groups. Duration: 2 months Chiropractic group vs brief massage/untreated groups Gonstead technique BP decreased in all 3 groups (largest change in control group) Small cohort

Roffers, Huber et al 201199 331 subjects subdivided in control (108), sham adjustment (117), treatment (106) Randomized control trial. Duration: 1 treatment Treatment vs control/placebo Specific thoracic (T5- Tl) chiropractic treatment Systolic and diastolic BP decreased significantly (p<0.0001) in the treatment group. No significant changes in the placebo and control groups The authors did not collect hypertensive medication history and current usage.
The trial was not double-blind. Anxiety might have increased the systolic and diastolic scores before treatment

Roffers, Stiles et al 2011100 331 subjects subdivided in control (108), sham adjustment (117), treatment (106) Randomized control trial. Duration: 1 treatment Treatment vs control/placebo Cervical (C3 to occiput CO) chiropractic adjustment Systolic and diastolic BP decreased significantly (p<0.0001) in the treatment group. No significant changes in the placebo and control groups The authors did not collect hypertensive medication history and current usage.
The trial was not double-blind. Anxiety might have increased the systolic and diastolic scores before treatment

Scott et al 2007105 20 healthy chiropractic students subdivided in chiropractic adjustment (10), control group(10) Randomized control trial. Duration: 1 treatment Treatment vs control Cervical HVLA A single cervical adjustment had no effect on systolic or diastolic BP No hypertensive patients, small cohort

Goertz et al 2016107 51 participants with prehypertension or stage 1 hypertension. Treatment group (24), control group (27) Randomized placebo- controlled clinical trial. Duration: 6 weeks Treatment vs control Toggle recoil upper cervical chiropractic Sham group: systolic BP (-4.2 mmHg), diastolic BP (-1.6 mmHg). Treatment group: systolic BP (0.6 mmHg); diastolic BP (0.7 mmHg). The difference was not statistically significant. No serious adverse events noted Patients in treatment group treated with antihypertensive medications were not washed out. The sham procedure was not validated for BP studies

Goertz et al 2002108 140 subjects with high to normal BP or stage I hypertension subdivided in diet group (69) and chiropractic group (71) Randomized doubleblind controlled trial. Duration: 4 weeks Chiropractic treatment vs diet treatment High velocity, short- lever impulse/force applied directly to a joint space Systolic/diastolic BP average decrease in control group (-4.9/-5.6 mmHg). Systolic/diastolic BP decrease in treated group (-3.5/-4.0 mmHg). No statistically significant changes among groups Lack of a no treatment control group

Holt et al
2010109 70 patients subdivided in treated (35) and control (35) groups Randomized controlled clinical trial. Duration: 1 treatment Treatment vs control Diversified Systolic blood pressure (-3.9 mmHg, p=0.002) Average changes in blood pressure were not clinically significant

McKnight et al 198828 75 students undergoing routine chiropractic care (53 treated, 22 control group) Nonrandomized controlled clinical trial. Duration: 1 treatment Treatment vs control Cervical adjustment via Gonstead method Systolic BP (-2.8 mmHg, p<0.01), diastolic BP (-2.6 mmHg, p<0.01) were statistically significantly lower than the controls Average changes in blood pressure not clinically significant

McMasters et al 201329 24 prehypertensive or hypertensive stage 1, with or without medication Nonrandomized. Duration: 23 visits Pre-treatment vs posttreatment Adjustments from a full spine exam Average systolic/diastolic BPs (no statistically significant pre/post differences for pre-hypertensive patients, p>0.05).
Average systolic BP (-12.8 mmHg, p=0.009), average diastolic BP (-7.6, p=0.0012) for stage 1 hypertensive patients The patients were not randomized. No control group. High dropout rate. Lack of accounting of confounding determinants of hypertension (diet, exercise)

Schwartzbauer et al 1997104 21 male university baseball players aged 19-23 (9 treated, 12 controls) Longitudinal study with control group. Duration:
14 weeks Treatment vs control Upper cervical No statistically significant differences recorded for blood pressure in controls or treated subjects Small sample size

Morgan et al 1985110 29 randomly selected subjects Randomized placebo- controlled trial. Duration 18 weeks Treatment vs control Osteopathic spinal manipulation, occipito-atlantal and thoracolumbar No significant difference in the BP after manipulation Small sample size

Win et al 2015111 10 asymptomatic normotensive volunteers + 10 normotensive patients with acute neck pain Randomized controlled, cross-over. Duration: 1 treatment Pre-treatment vs posttreatment for both groups Upper or lower cervical, using high velocity, low amplitude Systolic BP (-11 mmHg, p<0.05) in asymptomatic normotensive volunteers.
Systolic BP (-10 mmHg, p<0.05) in normotensive patients with acute neck pain Small sample size. No control or sham group. Lack of control over variables (diet, exercise)

Nansel et al 1991112 24 healthy, asymptomatic, nonsmoking males (12 treated, 12 controls) Nonrandomized. Duration: 1 treatment Treatment vs control Unilateral lower cervical spinal adjustment No significant differences between adjusted and non-treated subjects in blood pressure Small sample size, nonhypertensive subjects

Welch et al 2008® 40 patients of 21-55 years old, non-hypertensive, no history of heart disease Randomized trial. Duration: 1 treatment Pre-treatment vs posttreatment Diversified cervical segment adjustment or a diversified thoracic segment adjustment Diastolic BP (-5.6 mmHg, p=0.038) only after cervical adjustments. No significant reductions for thoracic adjustments Non-hypertensive patients

Wickes 1980115 20 normotensive individuals Double blind. Duration: 1 treatment Pre-treatment vs posttreatment Thoracolumbar spinal manipulation Systolic BP (+4.0 mmHg) 5 minutes post-manipulation Non-hypertensive patients

Yates et al 198823 21 hypertensive patients (7 treatment, 7 placebo, 7 no treatment) Randomized placebo- controlled trial. Duration: 1 treatment Treatment vs placebo/control Adjusting instrument to thoracic spine (Activator) Systolic and diastolic blood pressure decreased significantly in the active treatment condition Small sample size

Younes et al 2017116 17 patients with acute back pain (10 treatment, 7 placebo) Randomized placebo- controlled trial. Duration: 1 week Treatment vs placebo Osteopathic spinal manipulation therapy No significant differences in the blood pressure Small sample size, nonhypertensive patients

Ward et al
2013117 36 healthy chiropractic college students with less than 32% body fat 3-arm randomized single-blind controlled trial. Duration: 1 treatment Treatment vs placebo/control Anterior thoracic manipulation of T1-4 No statistically significant or clinically relevant difference was shown amongst any between-group or within-group cardiovascular dependent variables Non-hypertensive patients

Ward et al 2015118 50 hypertensive patients Single blind, controlled trial. Duration: 1 treatment Treatment vs control Upper thoracic spinal manipulative therapy Short-term cardiovascular physiology is not affected by upper thoracic spine SMT in hypertensive individuals to a clinically relevant level Small sample size, the researchers did not include in the exclusion criteria, severe cardiovascular conditions or non-cardiovascular medications that could impact the cardiovascular system

Watanabe et al 2007119 11 young healthy adults Pre/post test comparison. Duration: 1 treatment Pre-treatment vs posttreatment Mechanically stimulate cervical manipulation Significant reductions in BP after application of the mechanical stimulus in the supine posture (p<0.05). The reduction peaked at 20 seconds post-stimulation. Non-hypertensive subjects, small sample size

Dimmick et al 2006120 70 Patients (35 treatment, 35 control) Nonrandomized, matched pair, controlled clinical trial Treatment vs control McTimoney technique of chiropractic manipulation No significant difference between controls and treatment group Possible selection bias, lack of blinding

First author, year	Participants	Study design	Control group	Type of CMT	Results	Limitations
Bakris et al 200788	50 patients with stage 1 hypertension subdivided in treated (25) and controls (25)	Double blind, placebo controlled. Duration: 8 weeks	Treatment vs placebo	Atlas/Upper cervical chiropractic adjustment	Systolic BP (treatment: -17+/-9 mmHg vs placebo: -3+/-11 mmHg, P<0.0001) Diastolic BP (treatment: -10+/-11 mmHg vs placebo: -2+/-7 mmHg, P=0.002). No adverse effects recorded	Should be confirmed in a larger trial

Toms 201290	42 patients subdived in 3 groups: 12 hypotensive, 12 nomiotensive, 18 prehypertensive or stage 1 or stage 2 hypertensive	Cohort study. Duration: 1 treatment	Pre-treatment vs posttreatment	Atlas orthogonal upper cervical adjustment	Hypotensive group: systolic BP (+13.83mmHg, p<0.0001); diastolic BP (+8.83, p=0.0003). Nomiotensive group: systolic BP (- 3.92, p= 0.1107); diastolic BP (-1.58, p=0.2486). Pre-hypertensive + hypertensive groups: systolic BP(-20.22mmHg, p<0.0001); diastolic BP (-6.83mmHg, p<0.0001). No adverse effects recorded.	Absence of a specific control group. Follow-up measurements did not measure the duration of the effects

Toms 201491	20 participants ( 10 placebo group, 10 therapeutic group)	Placebo-controlled, randomized, prospective longitudinal cohort study. Duration: 6 weeks	Controls vs treatment	Atlas orthogonal upper cervical chiropractic care	Systolic BP (-12.2mmHg, p<0.05); Diastolic BP (-7.2; p<0.05)	The effect on the diastolic values were not significant after 4 weeks

Ward et al 201292	48 nomiotensive college students (24 controls, 24 treated)	Single blind, randomized controlled trial. Duration: 24h	Controls vs treatment	Atlas cervical break	No significant differences before and after chiropractic care compared to head turn and no contact control	Non-hypertensive patients

Knutson 200194	110 patients (80 in test one, 30 in test two)	Comparison study	Test 1: controlled clinical trial with a treatment group and a control group. Test 2: controlled clinical trial with subjects as controls	Vectored upper cervical care	Test 1: Significant decrease in systolic blood pressure (p<0.001); Test 2: No significant decrease in systolic blood pressure	Lack of randomization, blinding, manipulated control group

Kessinger et al 201995	130 patients subdivided in 3 groups: 54 with low pulse pressure (<40mmHg), 29 with medium pulse pressure (40 49mmHg), 47 with high pulse pressure (>49 mmHg)	Observational comparison study	Pre-treatment vs posttreatment	Knee chest upper cervical	Pulse pressure (-8.9mmHg, p<0.01) in patients with hypertension	Lack of randomization, not a clinical trial

Plaugher et al 200297	Subdivided in 3 groups: 9 undertook chiropractic, 8 a brief massage, 6 untreated. Study duration: 2 months	comparison trial with 3 parallel groups. Duration: 2 months	Chiropractic group vs brief massage/untreated groups	Gonstead technique	BP decreased in all 3 groups (largest change in control group)	Small cohort

Roffers, Huber et al 201199	331 subjects subdivided in control (108), sham adjustment (117), treatment (106)	Randomized control trial. Duration: 1 treatment	Treatment vs control/placebo	Specific thoracic (T5- Tl) chiropractic treatment	Systolic and diastolic BP decreased significantly (p<0.0001) in the treatment group. No significant changes in the placebo and control groups	The authors did not collect hypertensive medication history and current usage. The trial was not double-blind. Anxiety might have increased the systolic and diastolic scores before treatment

Roffers, Stiles et al 2011100	331 subjects subdivided in control (108), sham adjustment (117), treatment (106)	Randomized control trial. Duration: 1 treatment	Treatment vs control/placebo	Cervical (C3 to occiput CO) chiropractic adjustment	Systolic and diastolic BP decreased significantly (p<0.0001) in the treatment group. No significant changes in the placebo and control groups	The authors did not collect hypertensive medication history and current usage. The trial was not double-blind. Anxiety might have increased the systolic and diastolic scores before treatment

Scott et al 2007105	20 healthy chiropractic students subdivided in chiropractic adjustment (10), control group(10)	Randomized control trial. Duration: 1 treatment	Treatment vs control	Cervical HVLA	A single cervical adjustment had no effect on systolic or diastolic BP	No hypertensive patients, small cohort

Goertz et al 2016107	51 participants with prehypertension or stage 1 hypertension. Treatment group (24), control group (27)	Randomized placebo- controlled clinical trial. Duration: 6 weeks	Treatment vs control	Toggle recoil upper cervical chiropractic	Sham group: systolic BP (-4.2 mmHg), diastolic BP (-1.6 mmHg). Treatment group: systolic BP (0.6 mmHg); diastolic BP (0.7 mmHg). The difference was not statistically significant. No serious adverse events noted	Patients in treatment group treated with antihypertensive medications were not washed out. The sham procedure was not validated for BP studies

Goertz et al 2002108	140 subjects with high to normal BP or stage I hypertension subdivided in diet group (69) and chiropractic group (71)	Randomized doubleblind controlled trial. Duration: 4 weeks	Chiropractic treatment vs diet treatment	High velocity, short- lever impulse/force applied directly to a joint space	Systolic/diastolic BP average decrease in control group (-4.9/-5.6 mmHg). Systolic/diastolic BP decrease in treated group (-3.5/-4.0 mmHg). No statistically significant changes among groups	Lack of a no treatment control group

Holt et al 2010109	70 patients subdivided in treated (35) and control (35) groups	Randomized controlled clinical trial. Duration: 1 treatment	Treatment vs control	Diversified	Systolic blood pressure (-3.9 mmHg, p=0.002)	Average changes in blood pressure were not clinically significant

McKnight et al 198828	75 students undergoing routine chiropractic care (53 treated, 22 control group)	Nonrandomized controlled clinical trial. Duration: 1 treatment	Treatment vs control	Cervical adjustment via Gonstead method	Systolic BP (-2.8 mmHg, p<0.01), diastolic BP (-2.6 mmHg, p<0.01) were statistically significantly lower than the controls	Average changes in blood pressure not clinically significant

McMasters et al 201329	24 prehypertensive or hypertensive stage 1, with or without medication	Nonrandomized. Duration: 23 visits	Pre-treatment vs posttreatment	Adjustments from a full spine exam	Average systolic/diastolic BPs (no statistically significant pre/post differences for pre-hypertensive patients, p>0.05). Average systolic BP (-12.8 mmHg, p=0.009), average diastolic BP (-7.6, p=0.0012) for stage 1 hypertensive patients	The patients were not randomized. No control group. High dropout rate. Lack of accounting of confounding determinants of hypertension (diet, exercise)

Schwartzbauer et al 1997104	21 male university baseball players aged 19-23 (9 treated, 12 controls)	Longitudinal study with control group. Duration: 14 weeks	Treatment vs control	Upper cervical	No statistically significant differences recorded for blood pressure in controls or treated subjects	Small sample size

Morgan et al 1985110	29 randomly selected subjects	Randomized placebo- controlled trial. Duration 18 weeks	Treatment vs control	Osteopathic spinal manipulation, occipito-atlantal and thoracolumbar	No significant difference in the BP after manipulation	Small sample size

Win et al 2015111	10 asymptomatic normotensive volunteers + 10 normotensive patients with acute neck pain	Randomized controlled, cross-over. Duration: 1 treatment	Pre-treatment vs posttreatment for both groups	Upper or lower cervical, using high velocity, low amplitude	Systolic BP (-11 mmHg, p<0.05) in asymptomatic normotensive volunteers. Systolic BP (-10 mmHg, p<0.05) in normotensive patients with acute neck pain	Small sample size. No control or sham group. Lack of control over variables (diet, exercise)

Nansel et al 1991112	24 healthy, asymptomatic, nonsmoking males (12 treated, 12 controls)	Nonrandomized. Duration: 1 treatment	Treatment vs control	Unilateral lower cervical spinal adjustment	No significant differences between adjusted and non-treated subjects in blood pressure	Small sample size, nonhypertensive subjects

Welch et al 2008®	40 patients of 21-55 years old, non-hypertensive, no history of heart disease	Randomized trial. Duration: 1 treatment	Pre-treatment vs posttreatment	Diversified cervical segment adjustment or a diversified thoracic segment adjustment	Diastolic BP (-5.6 mmHg, p=0.038) only after cervical adjustments. No significant reductions for thoracic adjustments	Non-hypertensive patients

Wickes 1980115	20 normotensive individuals	Double blind. Duration: 1 treatment	Pre-treatment vs posttreatment	Thoracolumbar spinal manipulation	Systolic BP (+4.0 mmHg) 5 minutes post-manipulation	Non-hypertensive patients

Yates et al 198823	21 hypertensive patients (7 treatment, 7 placebo, 7 no treatment)	Randomized placebo- controlled trial. Duration: 1 treatment	Treatment vs placebo/control	Adjusting instrument to thoracic spine (Activator)	Systolic and diastolic blood pressure decreased significantly in the active treatment condition	Small sample size

Younes et al 2017116	17 patients with acute back pain (10 treatment, 7 placebo)	Randomized placebo- controlled trial. Duration: 1 week	Treatment vs placebo	Osteopathic spinal manipulation therapy	No significant differences in the blood pressure	Small sample size, nonhypertensive patients

Ward et al 2013117	36 healthy chiropractic college students with less than 32% body fat	3-arm randomized single-blind controlled trial. Duration: 1 treatment	Treatment vs placebo/control	Anterior thoracic manipulation of T1-4	No statistically significant or clinically relevant difference was shown amongst any between-group or within-group cardiovascular dependent variables	Non-hypertensive patients

Ward et al 2015118	50 hypertensive patients	Single blind, controlled trial. Duration: 1 treatment	Treatment vs control	Upper thoracic spinal manipulative therapy	Short-term cardiovascular physiology is not affected by upper thoracic spine SMT in hypertensive individuals to a clinically relevant level	Small sample size, the researchers did not include in the exclusion criteria, severe cardiovascular conditions or non-cardiovascular medications that could impact the cardiovascular system

Watanabe et al 2007119	11 young healthy adults	Pre/post test comparison. Duration: 1 treatment	Pre-treatment vs posttreatment	Mechanically stimulate cervical manipulation	Significant reductions in BP after application of the mechanical stimulus in the supine posture (p<0.05). The reduction peaked at 20 seconds post-stimulation.	Non-hypertensive subjects, small sample size

Dimmick et al 2006120	70 Patients (35 treatment, 35 control)	Nonrandomized, matched pair, controlled clinical trial	Treatment vs control	McTimoney technique of chiropractic manipulation	No significant difference between controls and treatment group	Possible selection bias, lack of blinding