Development and assessment of the psychometric properties of a new scale (15 item PSB-CL) to monitor the psychosocial burden of chronic lymphoedema in filariasis

Introduction: Chronic lymphoedema (CL) of lymphatic filariasis causes severe psychosocial burdens (PSB) to its victims. Currently-established scales to measure PSB of CL are not culturally adaptable to Sri Lankan patients. In this study, we developed and assessed the psychometric properties of a disease-specific questionnaire (15 item PSB-CL). Methods and Results: A detailed literature search was done to identify scales related to PSB of CL patients. Questions were developed through collected expressions from semi-structured interviews with 46 CL patients. A response scale was developed from the collected pool of possible responses, and they were scored using a visual analogue scale. Face and content validity were carried out using an initial questionnaire (31 questions). They were reduced to 27 by removing unclear, ambiguous, double-stranded ones and those with value-laden words. This new questionnaire was administrated on 92 patients by a group of doctors for item reduction by the analysis of internal consistency (Cronbach’s alpha > 0.7) and factor analysis (Principal Component Analysis; Eigenvalues > 1). After the patient survey and factor analysis, the final questionnaire PSB-CL was formed with 15 questions that had four subscales (factors), physical, social, fear and humiliation. Patients (n=92) reported quite a large percentage (42% - 69%) of problems under each dimension. Conclusion: The scale to measure the psychosocial burden of chronic lymphoedema in lymphatic filariasis patients in Sri Lanka. Further validation of the tool is needed.