Cross-cultural adaptation and validation of the South African Pain Catastrophizing Scale (SA-PCS) among patients with fibromyalgia

Background: Pain catastrophization has recently been recognized as a barrier to the healthy development of physical functioning among chronic pain patients. Levels of pain catastrophization in chronic pain patients are commonly measured using the Pain Catastrophizing Scale (PCS). Objective: To cross-culturally adapt and validate the South African PCS (SA-PCS) among English-, Afrikaans- and Xhosa-speaking patients with fibromyalgia living in the Cape Metropole area, Western Cape, South Africa. Methods: The original PCS was cross-culturally adapted in accordance with international standards to develop an English, Afrikaans and Xhosa version of the SA-PCS using a repeated measures study design. Psychometric testing included face/content validity, internal consistency (Cronbach's alpha-alpha), test-retest reliability (intraclass coefficient correlations-ICC), sensitivity-to-change and cross-sectional convergent validity (by comparing the adapted SA-PCS to related constructs). Results: The cross-culturally adapted English, Afrikaans and Xhosa SA-PCS showed good face and content validity, excellent internal consistency (with Chronbach's alpha = 0.98, 0.98 and 0.97 for the English, Afrikaans and Xhosa SA-PCS, as a whole, respectively), excellent test-retest reliability (with ICC's of 0.90, 0.91 and 0.89 for the English, Afrikaans and Xhosa SA-PCS, respectively); as well as satisfactory sensitivity-to-change (with a minimum detectable change of 8.8, 9.0 and 9.3 for the English, Afrikaans and Xhosa SA-PCS, respectively) and cross-sectional convergent validity (when compared to pain severity as well as South African versions of the Tampa scale for Kinesiophobia and the revised Fibromyalgia Impact Questionnaire). Conclusion: The SA-PCS can therefore be recommended as simple, efficient, valid and reliable tool which shows satisfactory sensitivity-to-change and cross-sectional convergent validity, for use among English, Afrikaans and Xhosa-speaking patients with fibromyalgia attending the public health sector in the Western Cape area of South Africa.