title: Benign adverse events following chiropractic care for neck pain are associated with worse short-term outcomes but not worse outcomes at three months.
abstract: METHODS
  A prospective cohort study on chiropractic patients with neck pain.
  
  
  OBJECTIVE
  To examine the association between self-reported benign adverse events after chiropractic care for neck pain and the outcome measures namely, perceived recovery, neck pain, and neck disability.
  
  
  BACKGROUND
  Only 1 study has examined the association between adverse events and outcome in subjects with neck pain treated by chiropractors, which concluded that those receiving cervical spinal manipulation were more likely to report an adverse event compared to cervical mobilization, and those reporting an adverse event were less likely to have improved outcomes at all follow-up measurements.
  
  
  METHODS
  This was a prospective, multicenter, observational cohort study conducted in the private clinics of chiropractors throughout The Netherlands. All new, consecutive patients, between 18 and 65 years of age with neck pain of any duration, who had not undergone chiropractic or manual therapy in the prior 3 months, were eligible for recruitment. Self-reported questionnaires were administered at the first 3 visits and at 3 months. Multivariate multilevel logistic and linear regression analyses were used to evaluate the association between adverse events and recovery, neck pain, and neck disability. Outcomes were measured at the fourth visit and at 3 months.
  
  
  RESULTS
  In total, 529 patients were recruited who fulfilled the inclusion criteria. The response rate at 3 months was 90%. At the fourth visit, subjects who reported a benign adverse event or "intense" adverse event after any of the first 3 visits were less likely to be recovered, and had slightly worse levels of neck pain. However, the differences in neck pain were too small to be clinically meaningful. Intense adverse events, on the other hand, were not only associated with more neck disability but also clinically relevant differences. At 3 months, adverse events were not associated with better or worse outcomes for any of the three outcome measures examined.
  
  
  CONCLUSIONS
  Self-reported benign adverse events after chiropractic care for neck pain are associated with worse short-term outcomes. Intense adverse events are associated with more neck disability and clinically relevant differences at the short-term only. However, there is no association between adverse events and worse outcomes at 3 months.
authors.affiliation: EMGO-Institute, VU University Medical Center, Amsterdam, the Netherlands. SM.Rubinstein@vumc.nl
authors.forename: Sidney M
authors.initials: SM
authors.lastname: Rubinstein
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Knol
authors.forename: Charlotte
authors.initials: C
authors.lastname: Leboeuf-Yde
authors.forename: Maurits W
authors.initials: MW
authors.lastname: van Tulder
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006261:Headache / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D008297:Male; D026882:Manipulation, Chiropractic / Q000009:adverse effects*; D008875:Middle Aged; D019547:Neck Pain / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy*; D010147:Pain Measurement / Q000379:methods / Q000639:trends; D011446:Prospective Studies; D013995:Time; D016896:Treatment Outcome