Translation and cross-cultural adaptation of the Palliative Care Knowledge Scale (PaCKS) into European Portuguese and its measurement properties in chronic obstructive pulmonary disease and interstitial lung diseases

Background No instruments exist to assess palliative care knowledge among Portuguese with chronic respiratory diseases.Aim To translate and cross-culturally adapt the Palliative Care Knowledge Scale (PaCKS) into European Portuguese and explore its measurement properties in chronic obstructive pulmonary disease (COPD) and interstitial lung diseases (ILD).Methods Translation and cross-cultural adaptation procedures were followed. Internal consistency (Cronbach’s α); test-retest reliability [intraclass correlation coefficient with 95% confidence interval (ICC2,1 [95% CI]), standard error of measurement (SEM/SEM%), minimal detectable change at 95% confidence level (MDC95/MDC%) and Bland-Altman method]; floor/ceiling effects; and, construct validity [convergent/divergent, correlation (Spearman’s - rs) with the Bristol COPD Knowledge Questionnaire (BCKQ)/modified Medical Research Council dyspnoea questionnaire/lung function] were evaluated.Results Two forward translations/back-translations were conducted. Five experts approved the prefinal version. Cognitive debriefing involved 12 participants. Measurement properties were analysed in 102 people with COPD and 54 with ILD (73.1% male; 67.6 ± 10.0 years). PaCKS score was 11.0 [9.0–12.0] and 10.0 [8.8–11.0] in COPD and ILD, respectively. Internal consistency was acceptable (αCOPD = 0.76; αILD = 0.80). The test-retest reliability was good in COPD (ICC2,1 0.84 [0.77–0.89]) and ranged from good to excellent in ILD (ICC2,1 0.89 [0.78–0.94]). SEM/SEM% and MDC95/MDC% were 1.0/9.6% and 2.8/26.6%, and 1.0/10.1% and 2.7/28.0% in COPD and ILD, respectively. The Bland-Altman method did not suggest systematic bias, with 95% limits of agreement of approximately ±3.0. No floor/ceiling effects were observed, except for a ceiling effect in COPD (20.6%). The PaCKS/BCKQ correlation was significant, positive and moderate (rs = 0.40, p < 0.001) in COPD. Other correlations were non-significant and ranged from negligible to weak.Conclusion The European Portuguese PaCKS is now available and provides reliable and valid data on palliative care knowledge in COPD and ILD.