Recruitment bias in chronic pain research: whiplash as a model

Abstract

In science findings which cannot be extrapolated to other settings are of little value. Recruitment methods vary widely across chronic whiplash studies, but it remains unclear whether this generates recruitment bias. The present study aimed to examine whether the recruitment method accounts for differences in health status, social support, and personality traits in patients with chronic whiplash-associated disorders (WAD). Two different recruitment methods were compared: recruiting patients through a local whiplash patient support group (group 1) and local hospital emergency department (group 2). The participants (n=118) filled in a set of questionnaires: the Neck Disability Index, Medical Outcome Study Short-Form General Health Survey, Anamnestic Comparative Self-Assessment measure of overall well-being, Symptom Checklist-90, Dutch Personality Questionnaire, and the Social Support List. The recruitment method (either through the local emergency department or patient support group) accounted for the differences in insufficiency, somatization, disability, quality of life, self-satisfaction, and dominance (all p values <.01). The recruitment methods generated chronic WAD patients comparable for psychoneurotism, social support, self-sufficiency, (social) inadequacy, rigidity, and resentment (p>.01). The recruitment of chronic WAD patients solely through patient support groups generates bias with respect to the various aspects of health status and personality, but not social support. In order to enhance the external validity of study findings, chronic WAD studies should combine a variety of recruitment procedures.

Neck Injury after Whiplash Trauma in a Defined Population in Northern Sweden – Long-Term Sick Leave and Costs of Low Productivity

“…Buitenhuis et al showed a high rate of sick leave among insurance claimants [16]. Differing recruitment methods likely explain the differences, and our lower figures [29]. Borchgrevink et al, in an ED-based study, found that 27% of 426 patients had been on sick leave, while Karlsborg et al reported a median absence from work of six days (0 days-9 months) [30,31].…”

Sex Differences in Patients with Chronic Pain Following Whiplash Injury: The Role of Depression, Fear, Somatization, Social Support, and Personality Traits

“…The data obtained from these subjects have been analyzed previously with respect to determinants of long‐term functioning following whiplash injury as well as to recruitment bias in chronic pain research, but not with respect to possible sex differences, which is the focus of this study.…”

Endogenous pain inhibition is unrelated to autonomic responses in acute whiplash-associated disorders

“…Chronicity was defined as complaints persisting for at least 3 mo. A variety of recruitment procedures were used in order to prevent recruitment bias [26]. The inclusion criteria for the acute and chronic WAD group were experiencing symptoms resulting from a whiplash trauma and fulfilling the diagnostic criteria of WAD grade I to III as defined by the Quebec Task Force classification [1].…”