Context: Although adverse events in various types of manual therapy have been previously investigated, little is known about the incidence and types of adverse events that occur after osteopathic manipulative treatment (OMT).

Objective: To estimate the incidence and characterize the types of adverse events that patients report after OMT and prior to leaving the office to increase the likelihood of identifying adverse events caused by OMT.

Methods: As part of a prospective study evaluating the use and effectiveness of OMT, patients assessed how they felt immediately after OMT compared with before OMT using a 5-point ordinal rating scale (much better, better, about the same, worse, much worse). For patients who indicated they felt their condition had changed, a follow-up, open-ended question asked them to describe how it had changed. Patients who felt worse or much worse were considered to have experienced an adverse event. Two reviewers independently coded the types of adverse events based on the descriptions provided by the patients. Generalized logistic regression models were used to calculate incidence rates and 95% CIs for the types of adverse events. These models were also used to calculate the ORs and 95% CIs for associations of adverse events with demographic characteristics and with individual OMT techniques after accounting for demographic characteristics.

Results: Immediately after OMT, 884 patients provided data at 1847 office visits (663 [76%] women; 794 [92%] identified as white; mean [SD] age, 51.8 [15.8] years). Patients reported they felt worse or much worse immediately after OMT at 45 office visits; the incidence rate for adverse events was 2.5% (95% CI, 1.3%-4.7%). Pain/discomfort was the most commonly identified type of adverse event (16 [0.9%]; 95% CI, 0.5%-1.6%). Insufficient information was provided to determine the type of adverse event at 20 office visits. Women reported adverse events more frequently than men (OR, 13.9; 95% CI, 1.7-115.6; P=.01).

Conclusion: The incidence of adverse events immediately after OMT, most commonly pain/discomfort, was lower than previous reports from other manual medicine disciplines. Larger studies are needed to determine the incidence of serious adverse events and to assess adverse events that occur in the days following OMT.