A comparison of the Barthel index and Nottingham extended activities of daily living scale in the assessment of disability in chronic airflow limitation in old age

Abstract

Introduction: there is no disease-specific instrument for measuring activities of daily living (ADLs) in elderly patients with chronic airflow limitation (CAL). We assessed sensitivity, specificity and positive and negative predictive values of two ADL scales: the Barthel index and the Nottingham extended ADL scale in elderly people with and without CAL. Methods: the Breathing Problems Questionnaire was used as a measure of quality of life (a low score indicates good quality of life) in 96 outpatients (56 men) with CAL aged 70-93 (mean 78) years and 55 community-dwelling controls (23 men) aged 71-90 (mean 78) years with normal lung function drawn from a recent community survey. CAL subjects had been clinically stable for > 6 weeks. All subjects were cognitively intact. Results: mean best 1 s forced expiratory volume/forced vital capacity was 45.5% (SE 1.4) in CAL subjects and 71.4% (SE 1.3) in controls. All CAL subjects considered themselves disabled and had higher breathing questionnaire scores [geometric mean scores: 39.5 (range 13 -112) vs 4.8 (range 0.6-40) for controls; t = 13.4, P < 0.0001]. However, the Nottingham extended ADL index (threshold > 18) discriminated better than the Barthel index (threshold > 17) in terms of sensitivity (76% vs 190%; χ2 = 60.9, P < 0.0001) and negative predictive value (75% vs 40%; χ2 = 20.2, P < 0.0001). Altering the Barthel threshold did not improve its performance. Multiple regression analysis showed that variability in physiological and psychological variables related to CAL predicted variability in Nottingham extended ADL score (R2 = 0.71) but not in Barthel score. Conclusions: the Barthel index underestimates disability in CAL in old age. The Nottingham extended ADL discriminates better between normal old people and those with CAL.