Exploring the definition of «acute» neck pain: a prospective cohort observational study comparing the outcomes of chiropractic patients with 0–2 weeks, 2–4 weeks and 4–12 weeks of symptoms

BACKGROUND: Neck pain is a common complaint in chiropractic patients. Amongst other baseline variables, numerous studies identify duration of symptoms as a strong predictor of outcome in neck pain patients. The usual time frame used for ‘acute’ onset of pain is between 0 and 4 weeks. However, the appropriateness of this time frame has been challenged for chiropractic low back pain patients. Therefore, the purpose of this study was to compare outcomes in neck pain patients with 0–2 vs 2–4 and 4–12 weeks of symptoms undergoing chiropractic treatment. METHODS: This is a prospective cohort observational study with 1 year follow-up including 495 patients whose data was collected between October 2009 and March 2015. Patients were divided into high-acute (0–2 weeks), mid-acute (2–4 weeks) and subacute (4–12 weeks) corresponding to duration of their symptoms at initial treatment. Patients completed the numerical pain rating scale (NRS) and Bournemouth questionnaire for neck pain (BQN) at baseline. At follow-up time points of 1 week, 1 month, 3 months, 6 months and 1 year the NRS and BQN were completed along with the Patient Global Impression of Change (PGIC) scale. The PGIC responses were dichotomized into ‘improved’ and ‘not improved’ patients and compared between the 3 subgroups. The Chi-square test was used to compare improved patients between the 3 subgroups and the unpaired Student’s t-test was used for the NRS and BQN change scores. RESULTS: The proportion of patients ‘improved’ was only significantly higher for patients with symptoms of 0–2 weeks compared to 2–4 weeks at the 1 week outcome time point (p = 0.015). The NRS changes scores were significantly greater for patients with 2–4 weeks of symptoms compared to 4–12 weeks of symptoms only at 1 week (p = 0.035). CONCLUSIONS: The time period of 0–4 weeks of symptoms as the definition of “acute” neck pain should be maintained. Independent of the exact duration of symptoms, medium-term and long-term outcome is favourable for acute as well as subacute neck pain patients. TRIAL REGISTRATION: Not applicable for prospective cohort studies. Ethics approval prior to study EK 19/2009.