Table 1.

Adverse Events Reported in Randomized Clinical Trials of Effectiveness of Spinal Manipulative Therapy for Acute Low Back Pain

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Source	Sample Size	Method for Assessing Adverse Events	Adverse Events
Blomberg et al, 1993	149	Closed-end questionnaires at 1, 2, and 4 mo	Has a table of adverse effects by group; “The treatment hurts” was statistically significantly more likely in the group treated with SMT than continued medical care
Fritz et al, 2015	220	Open-end and closed-end questionnaire at 4 wk	12.0% of patients reported a total of 20 adverse effects from treatment including increased pain, stiffness, spasm, shooting pain, and fatigue
Goertz et al, 2013	91	Not specified	No serious adverse events (2 mild adverse events were reported in SMT group, both were pain that resolved in 24-48 h)
Hancock, 2007	240	Spontaneous reporting and open-ended questions	No serious adverse reactions associated with SMT
Heymann et al, 2013	100	Not specified	Safety analysis showed no unexpected untoward events in either group
Juni et al, 2009	104	Not specified	Two serious adverse events occurred in the experimental group (4%) and 2 in the control group (4%); in the experimental group there was 1 patient with acute pancreatitis and 1 patient with an acute loss of motor and sensory function due to a herniated disk after randomization, but before any SMT treatment was initiated; in the control group, there was 1 patient with symptomatic cholelithiasis and 1 patient with a femoroacetabular impingement syndrome
Morton et al, 1999	29	Not specified	No adverse effects for either group
Waterworth et al, 1985	108	Not specified	Adverse experiences with therapy were not specifically itemized, but their seriousness and drug relationship were recorded; patients receiving SMT experienced less adverse reactions to treatments on the second assessment (at 10-12 days of therapy) than patients receiving nonsteroidal anti-inflammatory drugs.

Abbreviation: SMT, spinal manipulative therapy.