Are nerve conduction studies necessary? The development and evaluation of a patient-completed screening version of the Carpal Tunnel Questionnaire for use in primary care
Thesis or dissertation
University of Exeter
Abstract Introduction: Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment seen within the outpatient orthopaedic clinic; therefore assessment and management of this common condition is of significant importance. Traditionally diagnosis has been made through detailed questioning; clinical examination and nerve conduction studies (NCS). There is however no true consensus as to the gold standard assessment of CTS and the use of NCS can confer additional costs and delay treatment. Previous studies have explored methods of predicting the presence of CTS including the clinician-administered Carpal Tunnel Questionnaire (CTQ) (Kamath and Stothard, 2003). The aim of the present studies is therefore to explore the versatility of the CTQ to see how a novel Patient-completed Version of the CTQ compares to the original Clinican-completed version. Psychometric properties of the questionnaire will be explored together the economic impact of integrating both versions within an orthopaedic care pathway. A further aim is to answer whether the CTQ more effective and cost-effective than NCS for patients referred to an orthopaedic clinic with suspected CTS. Method: 100 patients referred for further investigation of suspected CTS were assessed using parallel patient and clinician-completed versions of the CTQ and results were subsequently compared with those obtained from NCS. Item analysis explored each of the nine constructs of the questionnaire and the original scoring algorithm was validated using binary logistic regression and compared with alternative algorithms. Sensitivity and specificity of the questionnaire when compared to results of NCS was explored using Receiver Operating Characteristic (ROC) analyses. Inter-rater reliability was explored through Pearson’s correlation coefficient. Economic analysis and modelling was carried out to explore potential cost savings of use of the questionnaire rather than NCS for those with suspected CTS. Results demonstrated sensitivity of 92% and specificity of 54.67% (positive predictive value 95.35%) for the patient-completed questionnaire and 96% sensitivity with 70.67% specificity (98.15 positive predictive value) for the clinician-completed questionnaire when used to predict the outcome of NCS. Binary logistic regression confirmed the original scoring algorithm and a revised algorithm did not significantly improve sensitivity. Adoption of the clinician-completed CTQ would have screen out 54% of referrals for NCS, which in the case of the study site would have conferred cost savings of £73,305 per annum (base upon a referral rate of 750 per annum). The patient-completed CTQ in the current sample resulted in 43% of referrals with suspected CTS not requiring NCS to assist in diagnosis with a potential saving of £58,372.5 per annum. There are further considerations of the reduction in waiting times, which are explored further within the analysis. Conclusion: Economic evaluation is complex due to the variety of pathways adopted by different orthopaedic departments. While the results of the Patient-complete version of the CTQ may not be as convincing as the clinician completed the study does provide validation for its use and expands the versatility of this useful adjunct to the assessment of CTS. Both versions could potentially confer significant cost savings and reduce demands on investigative services, reducing waiting times and improving the patient journey in suspected CTS.
Strategic Health Authority
Edwards, C. & Frampton, I. (2014) Predicting the outcome of nerve conduction studies in patients with suspected carpal tunnel syndrome: using an existing carpal tunnel assessment tool. Open Journal of Therapy and Rehabilitation 2;57-62.
Doctor of Clinical Research