Prognostic factors for persistent pain after a first episode of nonspecific idiopathic, non-traumatic neck pain: A systematic review. 
Prognosis of acute idiopathic neck pain is poor.  An overview of modifiable and non-modifiable prognostic factors for the development of chronic musculoskeletal neck pain after an episode of idiopathic, non-traumatic neck pain is needed.  Identify prognostic factors for pain intensity and perceived non-recovery at three, six and 12 months after a first episode of idiopathic, non-traumatic neck pain.  Systematic review METHODS: Systematic literature search up to October 21, 2017 for prospective prognostic studies with main outcomes perceived non-recovery and pain intensity.  The QUIPS was used for quality assessment.  Out of 2737 screened articles six prospective studies with high-risk-of-bias were identified, analyzing 47 and 43 factors for the outcome variables 'pain intensity' and 'perceived non-recovery', respectively.  Based on univariate- and multivariate analyses we found moderate evidence for 'age> 40 years' and 'concomitant back pain' to be prognostic for 'pain intensity'.  For the outcome 'perceived non-recovery' at 12 months, we found moderate evidence for both 'a previous period of neck pain' and 'accompanying headache' as prognostic variables for persistent pain, based on univariate analysis.  No prognostic factor was found which was retained in more than one multivariate analysis for the outcome variable 'perceived non-recovery'.  However, the quality of the evidence for these prognostic factors was low to very low.  This review identifies prognostic factors for neck pain, of which only a few are modifiable.  Further research is needed before drawing definite conclusions about the prognostic value of these factors.