Cross‐culture adaptation and validation of English version of Rheumatoid Arthritis Knowledge Assessment Scale (RAKAS) in patients with rheumatoid arthritis.

Aim: To carry out cross‐culture adaptation and validation of the English version of Rheumatoid Arthritis Knowledge Assessment Scale (RAKAS) in patients with rheumatoid arthritis (RA). Methods: A cross‐sectional study was conducted for 2 months in 2 tertiary care hospitals in Karachi, Pakistan. Sample size was calculated based on item‐subject ratio. The translation was carried out using standard procedures for translation and cross‐culture adaptation. The validation process included estimation of discrimination power, item difficulty index, factorial, convergent, construct and known group validities and reliability. Reliability of the scale was estimated using Kuder‐Richardson Formula 20 and a value of σ2 ≥ 0.6 was acceptable. SPSS v23, Remark Classic OMR v6 software and MedCalc Statistical Software v16.4.3, were used to analyze the data. The study was approved by the relevant ethics committee (IRB#NOV:15). Results: The mean score was 7.68 ± 2.52 (95% CI: 7.31‐8.05) for 177 patients. The σ2 = 0.601, that is, >0.6, test‐retest reliability ρ =.753, P <.05. The average discrimination power = 47.27, average Item Difficulty Index = 0.557. The fit indices were acceptable in a range that established its factorial validity and average factor loading was ≥0.7 which established convergent validity. A significant association (χ2 = 33.074, P <.01) between score interpretation and previous counseling by pharmacists established its construct validity. A significant association (χ2 = 19.113, P <.05) between score interpretation and patient occupation established known group validity. Conclusion: The English version of RAKAS was deemed a reliable and validated tool to measure knowledge about disease in Pakistani patients with RA. [ABSTRACT FROM AUTHOR]