Osteopathic Manipulation as a Method of Cortisol Modification: A Systematic Review

Methods

• Articles analyzed: 4
• Search string: “osteopathic” AND “cortisol”
• Criteria of inclusion: studies with before and after treatment data; inclusion of a control group; presence of precise numerical data including mean, standard deviation, effect size, sample size (number of people recruited); salivary or plasma cortisol measurements; OMT as a treatment.

• Criteria of exclusion: studies not in English; studies published before 2000; measurements other than salivary or plasma sampling for cortisol; lack of precise and well-quantifiable numerical evaluations of the outcomes (eg, studies in which the outcomes were reported as simple percentages and nothing else) were excluded.

Characteristics of the studies

• 3 studies on salivary cortisol
• 1 study on plasma cortisol
• assessment of the quality of the studies through RoB (risk of bias in randomized trials)
  • studies of a medium quality

Participants

• Total: 135 people, 68 in the OMT Group and 67 in the Control Group
  • 126 people with salivary cortisol, 62 in the OMT Group and 64 in the Control Group
  • 9 people with plasma cortisol, 6 in the OMT Group and 3 in the Control Group

Interventions and evaluations

• Evaluation of changes in salivary or plasma cortisol measured as ug/ml
  • the circadian nature of cortisol was not considered in the analyses
• Interventions:
  • OMT
  • Sham treatment

Results

• Outcomes: cortisol was shown to be reduced more by OMT than by sham treatment (-0.10 μg/dl, with a 95% confidence interval between -0.15 and -0.04) in the comparison between before and after treatment. The effect size was medium, but did not reach statistical significance (-0.46, with a 95% confidence interval between -1.40 and 0.48).
  The studies analyzed were homogeneous.

Discussion

The meta-analysis showed a greater effect of OMT than sham in reducing salivary cortisol, although the overall result was not significant.

Such a result was not unexpected given that cortisol modifications are often quite small after just one treatment. Therefore studies with multiple treatment sessions are needed. In addition, different techniques or approaches should be tested individually, as many different techniques are grouped under the term OMT, which could possibly sort different effects on cortisol.

More attention should also be paid to the changes occurred in the circadian rhythms of cortisol and in other vital parameters, as well as to the use of other rating scales for stress and cortisol levels in comparison to each other.

Considering that high cortisol levels are correlated with other outcomes, such as dementia, cardiovascular risk, depression and complications in the elderly, all conditions that require complex management, the availability of a treatment able to act directly on cortisol can certainly be useful. Bearing in mind that such effect would be parallel to the OMT effects on the rest of the body.