Research Review by Dr. Michael Haneline©


Nov. 2007

Study Title:

The benefits outweigh the risks for patients undergoing chiropractic care for neck pain: A prospective, multicenter, cohort study


Rubenstein S et al.

Publication Information:

Journal of Manipulative and Physiological Therapeutics 2007; 30(6): 408-18.


Studies have suggested that manipulation is an effective therapy for nonspecific neck pain, though associated adverse events have been reported in the literature. Rare manipulation-related strokes have been well-documented, but little is known about the more common adverse events, which are mostly mild and self-limiting.

Previous studies on this topic have utilized observational research designs and only one of them specifically targeted cervical spine manipulation (CSM) to determine whether adverse events had an influence on outcome measures (Hurwitz et al. – see below). In this particular study, patients with adverse events were less satisfied with care, perceived less improvement, and had more pain and disability on follow-up.

The primary objective of this practice-based study was to describe the clinical outcomes, as well as adverse events that occurred following the first 3 treatments in neck pain patients presenting to chiropractic offices.

All 189 members of the Netherlands Chiropractors’ Association were invited to take part in the study via mailed flyers and personal contacts. Seventy-nine of them accepted the invitation. Patients were recruited from new patients presenting to the participating chiropractors’ offices and were included if they had “neck or neck-related pain”, which was further defined as cervicothoracic and/or periscapular pain. Patients had to be between 18 and 65 years of age, and not have received chiropractic care or manual therapy in the previous 3 months. Exclusion criteria were:
  • a red flag condition (e.g., suspected infection, fracture, tumor, metastasis, or intravenous drug use)
  • any other condition thought to be a contraindication for cervical spine manipulation (e.g., luxation or instability of the vertebral articulations)
Patients completed self-administered questionnaires in the chiropractic offices at baseline and prior to treatment on their second and fourth visits. Outcome measures utilized in this study were:
  • pain, on an 11-point numerical rating scale (NRS)
  • disability, via the Neck Disability Index (NDI)
  • perceived recovery, using a 6-point Likert scale that ranged from the patient being “much worse” to “completely improved”
  • treatment satisfaction, using a 10-item instrument along with 2 other questions: “How satisfied were you with the treatment by your chiropractor?” and “Would you visit a chiropractor again with this or a similar complaint?”
  • adverse events following treatment (see below)
An adverse event was defined as either a new related complaint that was not present at baseline, or a worsening of the presenting complaint by >30%. Adverse events could include:
  1. increased pain/stiffness at the treated area
  2. increased pain/stiffness in another treatment-related area
  3. headache
  4. tiredness/fatigue
  5. radiating pain into the arm or hand
  6. dizziness or lightheadedness
  7. nausea
  8. ringing in the ears
  9. confusion or disorientation
  10. depression or fear
  11. any other reaction not specified
The severity of adverse events was graded using an 11-point NRS, with the worst category defined as “intense”. The authors pointed out the difference between “intense” and “serious” adverse events. The “intense” variety referred to adverse events that resulted in an intensity score >8 on the 11-point NRS, while “serious” adverse events referred to events that caused death, life-threatening situations, the need for hospital admission, or disability.

It is important to note that the type of treatment provided was left to the discretion of each chiropractor.

Pertinent Results:

  • The patient recruitment period lasted 7 months and produced a total of 579 patients. However, 50 were excluded, with reasons given, resulting in a final cohort 529 patients.
  • Follow-through was acceptable, considering this was a practice-based study, with 96% and 87% of the study population returning for a second and fourth visit, respectively, and 90% and 92% responding at 3 and 12 months, respectively.
  • A total of 4891 treatment sessions were recorded, with the chiropractors delivering 9.3 ± 5.3 (mean ± SD) treatments per patient.
  • Most of the chiropractors (78%) used the diversified method of spinal manipulation. Other commonly used chiropractic methods included Activator (instrument), soft-tissue or trigger point therapy, and mobilization. Nearly all of the subjects (97%) received some form of manipulation.
  • In addition to neck pain, 94% of the patients had at least one coexisting symptom at baseline (e.g., headache, tiredness, dizziness, radiating pain), and half of the group had 3 or more additional symptoms.
  • Coexisting symptoms improved considerably by the second and fourth visits, affecting only 34% and 22%, respectively, of the group. However, the prevalence of these concomitant symptoms returned to nearly baseline values at 3 and 12 months, when most of the patients were no longer under care.
  • Clinical outcome measures for neck pain and disability showed steady improvement for the first 3 months, but no further improvement was detected at 12 months.
  • “Recovery” was reported by 21% and 48% of the subjects at their second and fourth visits, respectively, and by 65% and 64% at 3 and 12 months, respectively.
  • Adverse events following treatment were mostly musculoskeletal or pain related and were reported by 48% of the group after their first visit and 26% after their second or third visit. Altogether, 56% of the cohort reported an adverse event following any of the first 3 treatments. More than 80% of those who reported adverse events considered them to have no influence or minor influence on their activities of daily living.

Conclusions & Practical Application:

The authors pointed out that only one other study (Hurwitz et al.) has investigated both positive and negative clinical outcomes in neck pain patients undergoing chiropractic treatment, although it had a smaller sample size. Interested readers should review this paper as well.

Two major findings of this study should be emphasized:
  1. Regarding risks, even though more than 50% of the patients experienced an adverse event, only 1% of them reported to be much worse at the end of the study. Furthermore, no serious neurologic complications were reported.
  2. Regarding benefits, most patients experienced benefit from chiropractic treatment rather quickly, even though many of them had chronic conditions and had undergone prior care.
A number of the same symptoms that are commonly thought to be caused by manipulative treatment, such as headache, nausea, dizziness, tiredness, or depression, were present in many of the subjects at baseline, and were sometimes of severe intensity. Accordingly, it is possible to mistakenly ascribe previously unreported symptoms to the treatment, when they were actually present prior to the start of treatment. This may have artificially inflated the percentage of those reporting adverse events.

It is relevant to note that this study confirms earlier work suggesting that most adverse events occur near the beginning of a treatment regimen. Clinicians may want to consider this when designing treatment plans, perhaps limiting certain interventions early on, when patients seem most likely to have a reaction.

Several study limitations were listed, including the use of questionnaires that have not been validated; the potential for response, recall, and selection bias; no use of a control group; and the fact that imaging was not obtained for most patients.

Since neck pain patients responded so quickly to care in this study, particularly within the first 3 treatments, and since most patients remained stable after 3 months of care, clinicians should recognize that extended treatment programs might have limited added value, especially when patients do not improve by their fourth visit.

The authors concluded that, even though adverse events following treatment are common and sometimes of severe intensity, the results of this study show that the benefits of chiropractic care for neck pain outweigh the potential risks.

Additional Reference:

Hurwitz EL, Morgenstern H, Vassilaki M, Chiang LM. Adverse reactions to chiropractic treatment and their effects on satisfaction and clinical outcomes among patients enrolled in the UCLA Neck Pain Study. J Manipulative Physiol Ther 2004;27:16-25.