Muscle weakness is related to utilization of health care resources in COPD patients

The factors determining utilization of health care resources in patients with chronic obstructive pulmonary disease (COPD) are poorly understood. In order to obtain insight into these factors, we studied the utilization of health care resources in 57 stable COPD patients with a forced expiratory volume in one second (FEV1) of 36 +/- 9% predicted. Patients were divided into two groups: admitted at least twice in the last year (high medical consumption; n = 23) or not admitted in the last year (low medical consumption; n = 34). Other variables related to utilization of health care resources studied were; the number of hospital days; the number of out-patient visits to a pulmonary department in the last year; and the average daily dose (ADD) of corticosteroids taken in the last 6 months. The actual cost of utilization of health care resources, however, was not studied. In addition, pulmonary function, serum electrolytes, blood gas values, 6 min walking distance, respiratory and peripheral muscle force, and appraisal of self-care agency (ASA score) were studied. Pulmonary function, serum electrolytes, blood gas values, ASA score and walking distance were not different between the two groups (e.g. FEV1 36 +/- 8 vs 36 +/- 10% pred). Respiratory muscle forces tended to be lower in the high medical consumption group, this tendency almost reaching statistical significance for maximal expiratory pressure (PE,max) (p = 0.08). Peripheral muscle force, however, was clearly reduced in the high medical consumption group (quadriceps force 63 +/- 20 vs 82 +/- 26% pred; p < 0.05). The number of admissions, the number of hospital days, the number of out-patient visits, and ADD were interrelated and also related to ventilatory and peripheral muscle force (r -0.18 to -0.38). This relationship was statistically significant for PE,max, whilst a similar tendency was present for maximal inspiratory pressure (PI,max). In stepwise multiple regression analysis, only quadriceps force was a significant determinant of utilization of health care services. We conclude that utilization of health care services in patients with chronic obstructive pulmonary disease is related to ventilatory and peripheral muscle force. Whether or not reduced muscle force is simply an expression of disease severity remains to be determined.