Study designs of evaluations included in the review
Randomised controlled trials and controlled trials were eligible for inclusion. Single case studies and laboratory and simulation studies were excluded.
Specific interventions included in the review
Comparisons of PRFN with no treatment, placebo or other interventions were eligible for inclusion. The included study compared PRFN to a sham machine.
Participants included in the review
Studies of patients of any age or ethno-cultural group, treated for persistent cervical pain following whiplash associated with motor vehicle or other accidents, were eligible for inclusion, whether or not the diagnosis was proven with local anaesthetic injection into nerves supplying the painful joint(s). No exclusion was made due to co-morbidity. The patients in the included study all had whiplash attributable to motor vehicle accident and had failure of conventional therapy.
Outcomes assessed in the review
To be included in the review, the studies had to report at least one measure relating to a health outcome, defined as 'a change in a patient's current health status that can be attributed to antecedent health care'. The studies had to have a minimum observational period of 4 weeks. The outcomes reported in the included study included pain, activities of daily living and psychological distress.
How were decisions on the relevance of primary studies made?
The search results were reviewed independently by two reviewers, and the inclusion criteria were applied to each article. Any disagreements were resolved by discussion. All articles that appeared to meet the criteria were requested in full-text form. Full articles were assessed for inclusion independently by two reviewers.