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Published online 2019 Mar 5. doi: 10.1136/bmj.l689

Table 2

Summary of adverse event assessments among trials included in systematic review of spinal manipulative therapy (SMT) for chronic low back pain

Study, sample sizeMethods used to assess adverse eventsAdverse events assessedAdverse events reported (for SMT or control group)
Balthazard 2012, n=42Not reportedAny adverse eventNo adverse events reported; but one patient dropped out in each group owing to severe pain

Bronfort 2011, n=301Self reported throughout follow-upAny adverse event“All adverse events were transient in nature, required little or no change to activity levels, and were considered non-serious,” 6 (2%) patients were treated with rescue pain medication during treatment period: severe back pain, acute flare-up of low back and buttock pain, neck pain, and inability to sleep because of pain. Four (1%) patients reported similar adverse events but declined rescue medication

Brønfort 1996, n=174Not reportedAny adverse eventNon-steroidal anti-inflammatory drug group: 2 (4%) patients developed severe nausea and vomiting and subsequently discontinued the study, 8 (16%) developed substantial nausea and dyspepsia, and 1 (2%) developed severe tinnitus; SMT+exercise groups: 1 (2%) patient discontinued exercise because she did not tolerate it well and 7 (14%) developed muscle soreness and stiffness, including neck pain after exercise—these symptoms gradually abated and did not prevent completion of the study; 1 (1%) developed symptoms of a myocardial infarction unrelated to exercise. “Overall, both strengthening and stretching exercise and SMT were well tolerated”

Castro-Sanchez 2016, n=62Self reported after treatment and follow-upAny adverse eventNo adverse events reported

Cecchi 2010, n=210Not reportedAny adverse eventNo adverse events reported

Cook 2013, n=154Physiotherapists queried at end of studyAny adverse eventNo adverse events reported

Dougherty 2014a, n=181Assessed at each treatment visit and via phone calls during follow-up periodAny adverse event243 adverse events were reported during the study: 55% in exercise group and 45% in SMT group. Of 110 events reported in the SMT group, the Data Safety Monitoring Board (DSMB) judged 14 as definitely or probably associated with SMT. Most adverse events consisted of musculoskeletal soreness and resolved within study period. During the study period, 10 serious adverse events were reported (5 control group, 5 SMT group); DSMB judged none of the serious adverse events to be associated with the study intervention

Evans 1978, n=36Not reportedAny adverse event1 (3%) patient reported constipation after consumption of 24 codeine phosphate capsules in first 4 days; no serious adverse events reported

Ferreira 2007, n=240Not reportedAny adverse eventNo adverse events reported, one patient died, and one was admitted to hospital, in control group

Gudavalli 2006, n=235Not reportedAny adverse eventNo adverse events reported

Haas 2014, n=400Not reportedAny adverse event3 (1%) patients reported seeking care for symptomatic relief of low back pain exacerbation related to study, 1 (1%) lost several days of work followed by complete resolution during treatment phase, and 1 (1%) dropped out after an exacerbation associated with lifting a child; no serious adverse events reported

Hidalgo 2015, n=32Not reportedAny adverse eventNo serious or moderate adverse events reported

Hondras 2009, n=240Not reportedAny adverse event20 (8%) patients reported an adverse event, all resolved within 6 days, and none required referral for outside care. Adverse events in SMT groups consisted of soreness or stiffness. 1 patient reported a skin rash in drug group; no serious adverse events reported

Hsieh 2002, n=206Not reportedAny adverse event23 (12%) patients reported adverse events: 17 (11%) in control groups (combined), 6 (12%) in SMT group; adverse events were limited to transient exacerbations of symptoms, except for one case of constant tinnitus in a control group; 2 (4%) patients claimed SMT had aggravated their condition; no serious adverse events reported

Licciardone 2013, n=455Not reportedAny adverse event27 (6%) patients reported an adverse event; 9 (2%) reported a serious adverse event (“none was definitely or probably related to a study intervention” according to DSMB); no significant differences between groups in frequency of (serious) adverse events; 6 patients who received SMT developed a contraindication to continued study participation (SMT was adjudicated by DSMB to be possibly related to development in only one of these)

Muller 2005, n=115Not reportedAny adverse event3 (6%) patients in drug group experienced an adverse event; no serious adverse events reported

Rasmussen 2008, n=72Not reportedAny adverse event4 (11%) patients in SMT group reported worsening of low back pain versus 3 (8%) in control group; no serious adverse events reported

Senna 2011, n=93Not reportedAny adverse eventMost common were local discomfort and tiredness, which were transient and began within 24 hours after treatment, and were of mild to moderate severity; no serious adverse events reported

Skillgate 2007, n=409Self-reported events at a follow-up visitAny adverse eventMinor short term events limited to muscle soreness, tiredness, and increased pain, most commonly after first and second treatments; no serious adverse events reported

UK BEAM trial 2004, n=1334Monitoring by research team; not elucidated furtherSerious adverse events only, defined as admission to hospital or death within one week of treatmentNo serious adverse events reported

Walker 2013, n=183Self-reported events at each follow-up visitAny adverse event30 (33%) of patients in sham group and 39 (42%) in SMT group reported at least 1 adverse event; common adverse events were increased pain (sham 29%; SMT 36%), muscle stiffness (sham 29%; SMT 37%), and headache (sham 17%; SMT 9%). The relative risk was not significant for adverse event occurrence (1.24, 95% confidence interval 0.85 to 1.81), occurrence of severe adverse events (1.9, 0.98 to 3.99), adverse event onset (0.16, 0.02 to 1.34), or duration of adverse events (1.13, 0.59 to 2.18); no serious adverse events reported

Xia 2016, n=192Not reportedNot reportedNo serious adverse events reported

Zaproudina 2009, n=131Not reportedNot reported1 (2%) patient in SMT group and 2 (3%) in control group discontinued treatment owing to worsening of low back pain; no serious adverse events reported