The de Quervain's screening tool: validity and reliability of a measure to support clinical diagnosis and management.

BACKGROUND: Studies into the effectiveness of interventions for upper limb soft tissue disorders have been hampered by a lack of consistently used diagnostic criteria, meaning that comparison of research results is a problem. To aid homogeneous recruitment into a study of de Quervain's disease, a de Quervain's screening tool (DQST) was developed. This could also be used to facilitate clinical diagnosis and management in practice.

AIMS: To provide evidence for the content and construct validity and test-retest and inter-rater reliability of the DQST.

METHOD: The study was conducted in an acute care, outpatient hand unit in a district general hospital. Three convenience samples of: 59 people with de Quervain's disease; 18 with carpal tunnel syndrome (CTS) and 16 with osteoarthritis (OA) of the carpometacarpal (CMC) joint were recruited. The DQST diagnostic criteria were initially generated from a literature review. Content validity was then established by expert doctors with an interest in upper limb musculoskeletal disorders (n = 7) rating the relevance of the seven items included. The DQST was then tested in people either already diagnosed with, or reported as having some of the symptoms of, de Quervain's disease. Construct validity was tested with people with CTS or OA of the CMC joint.

RESULTS: The median DQST score was 5 (Interquartile range IQR = 4-6) out of a possible seven diagnostic criteria. Inter-rater reliability was excellent (Intra-class coefficient [ICC] = 0.85; 95% confidence interval [CI] = 0.75, 0.91). Test retest reliability was good (ICC = 0.64; 95% CI = 0.20, 0.87). Sensitivity (Se) and specificity (Sp) testing (Se = 1.00; Sp = 1.00) demonstrated that the DQST discriminated between people with de Quervain's disease, CTS or OA of the CMC joint.

CONCLUSIONS: The DQST is a valid, reliable tool which could be of assistance in aiding correct diagnosis for recruitment to clinical trials and in clinical practice. Future research is recommended to further examine retest reliability with a larger sample size and to identify the commonest diagnostic criteria required for inclusion.