Added value of co-morbidity in predicting health-related quality of life in COPD patients

The extent to which a chronic obstructive pulmonary disease (COPD) patient is impaired ill health-related duality of life (HRQoL) is only to a small e xtent reflected in clinical and demographical measures. As the influence of comorbidity on HRQoL is less clear, we investigated the added value of 23 common diseases in predicting HRQoL in COPD patients with mild to severe ai rways obstruction. COPD patients from general practice who appeared to have an forced expirato ry volume in 1 sec/inspiratory vital capacity(FEV1/IVC) < predicted -1.64 s o, FEV1< 80% predicted, FEV1 reversibility < 12% and a smoking history, wer e included (n=163). HRQoL was assessed with the short-form-36 (SF-36) and t he presence of comorbidity was determined by a questionnaire, which asked f or 23 common diseases. All domains of the SF-36 were best predicted by the presence of three or mo re co-morbid diseases. FEV1 % predicted, dyspnoea and the presence of one o r two diseases were second-best predictors. Co-morbidity explained an addit ional part of the variance in HRQoL, particularly for emotional functioning (DeltaR(2)=0.11). When individual diseases were investigated, only insomni a appeared to be related to HRQoL. As HRQoL is still only partly explained, co-morbidity and other patient cha racteristics do not clearly distinguish between COPD patients with severe i mpairments in HRQoL and COPD patients with minor or no impairments in HRQoL . Therefore, it remains important to ask for problems in daily functioning and well-being, rather than to rely on patient characteristics alone.