DEVELOPMENT AND PSYCHOMETRIC TESTING OF IBADAN STROKE-SPECIFIC PAIN SCALE

Abstract

Post-stroke pain is a common and multifaceted condition that significantly limits stroke survivors' potentials for functional recovery. Appropriate assessment of post-stroke pain is useful in evaluating the effectiveness of interventions aimed at controlling it. Generic pain scales are inadequate in capturing the peculiarities of post-stroke pain. Literature search revealed no stroke-specific pain scale. A stroke-specific pain rating scale, the ‘Ibadan Stroke-Specific Pain Scale’(IbSSPS) was developed and psychometrically tested in this study. Development and psychometric testing of the IbSSPS were carried out using qualitative and quantitative research designs respectively. Potential scale items were generated through four sessions of Focus Group Discussions (FGDs) involving 18 purposively selected individuals with stroke-related pain at the University College Hospital, Ibadan. Different aspects of post-stroke pain and its impact on their daily functioning were explored. Items generated from the FGDs were grouped into four themes based on the domains of interest namely: pain location and severity, psychosocial functioning, physical functioning, and signs and symptoms. The items of IbSSPS were reviewed by a panel of clinical experts and pre-tested among another 30 stroke survivors to rule out ambiguity, establish comprehension and endorsement. A four-domain, 36-item IbSSPS, with scores ranging from 0 to 116 (higher score indicating higher pain status) was subsequently developed. The IbSSPS was tested for reliability and responsiveness among 56 (27 males and 29 females) consecutive stroke survivors (Index Group) and 56 (27 males and 29 females) apparently healthy age and sex-matched counterparts (Control) for known-group validity. The categorised verbal descriptor pain scale was used for convergent validity. Also, the IbSSPS was administered after a two-hour interval to assess the test-retest reliability and after six weeks to test responsiveness. Data were analysed using Mann-Whitney U, Spearman correlation, intraclass correlation coefficient (ICC), Cronbach’s alpha coefficient, Wilcoxon Sign rank test, standardised effect size and standardised response mean at p=0.05. The baseline IbSSPS median total score for the index group (37.0; range: 2 to 82) was significantly higher than the control group (3.0; range: 0 to 15). The IbSSPS score for pain location and severity domain was significantly correlated with the categorised verbal descriptor pain scale (r = 0.65). The other domains had weak to moderate correlations (r =0.29 to 0.58). The ICC ranged from 0.85 to 0.94 while Cronbach’s alpha ranged from 0.64 to 0.90 for the four domains. At 6 weeks, the IbSSPS also detected changes in pain status for all the domains: pain location and severity (from 6.8 to 4.6), psychosocial functioning (from 10.2 to 7.9), physical functioning (from 20.8 to 17.7), signs and symptoms (from 3.5 to 2.3) and total score (from 41.5 to 32.4). The standardised effect size and standardised response mean ranged from 0.31 to 0.70 and 0.50 to 0.90 respectively. The Ibadan Stroke-Specific Pain Scale is a reliable and responsive instrument for assessing post-stroke pain. The instrument is recommended for evaluating and tracking changes in pain experienced by stroke survivors.