Frailty and patient-reported outcomes in subjects with chronic obstructive pulmonary disease: are they independent entities?

INTRODUCTION There is a hypothesis that chronic obstructive pulmonary disease (COPD) is an accelerated ageing disease. Frailty is a geriatric syndrome characterised by physical, psychological and social vulnerability, thought to be a feature of ageing. The authors aimed to explore the relationship between frailty and physiological and patient-reported outcomes (PROs) in subjects with stable COPD. METHODS We administered the Kihon Checklist that has been validated for frailty screening. We also assessed patient-reported measurements of health status and dyspnoea using the COPD Assessment Test (CAT), the St. George's Respiratory Questionnaire (SGRQ), the Hyland Scale, the Medical Outcomes Study 36-item short-form (SF-36), the Baseline Dyspnea Index (BDI) and the Dyspnea-12 (D-12). Pulmonary function was also measured. RESULTS Of 79 consecutive COPD outpatients, 38 (48.1%), 24 (30.4%) and 17 (21.5%) patients were classified as robust, prefrail and frail, respectively. The total Kihon Checklist score was significantly weakly to moderately correlated with the CAT score (Spearman's rank correlation coefficient (Rs)=0.38, p<0.01), the SGRQ total score (Rs=0.65, p<0.01), the Hyland Scale score (Rs=-0.54, p<0.01), all subscale scores of the SF-36 (Rs=-0.64 to -0.31, p<0.01), the BDI score (Rs=-0.46, p<0.01) and the D-12 score (Rs=0.41, p<0.01). We found no or only weak correlations between the total Kihon Checklist score and lung function measurements. We found statistically significant between-group (robust, prefrail and frail) differences in most PRO scores. Using stepwise multiple regression analyses to identify the variables that predicted the total Kihon Checklist score, the SGRQ total score alone significantly explained 49.1% of the variance (p<0.01). DISCUSSION Frailty was significantly correlated with PROs, especially health status, unlike lung function. Frailty should be assessed in addition to PROs separately from lung function as part of multidimensional analyses of COPD.