Patient weighting of importance of asthma symptoms

Background-Quality of life measures are increasingly important in evaluatin g outcomes in asthma. If some asthma symptoms are more troublesome to patie nts than others, this may affect their contribution to outcome measures. Th is study was designed to assess the relative importance of common symptoms in adults with asthma. Methods-A postal survey using conjoint analysis was performed in 272 adults attending hospital outpatient clinics with moderately severe asthma. Patie nts were asked to chose between "symptom scenarios" offering different comb inations of levels of five common asthma symptoms over one week. Two versio ns of the questionnaire were used with identical scenarios presenting sympt oms in different orders. Different patients answered the two versions. Regr ession analysis was used to calculate symptom weights for daytime cough, br eathlessness, wheeze and chest tightness, and sleep disturbance. Results-Symptom order, percentage predicted peak expiratory flow (PEF), and symptoms in the week before the survey did not influence the choice of sce nario. In both questionnaires patients were more likely to choose scenarios with low levels of cough and breathlessness than low sleep disturbance, wh eeze or chest tightness. Regression weights for cough (-0.52) and breathles sness (-0.49) were twice those of wheeze (-0.25), chest tightness (-0.27), and sleep disturbance (-0.25). For 12% of patients cough dominated patient preferences, regardless of all other symptoms. Age was inversely related to weight given by patients to breathlessness. Conclusions-The prominence of cough among other asthma symptoms was unexpec ted. Daytime cough and breathlessness had greater impact for patients than wheeze or sleep disturbance. Age influenced symptom burden, with younger pa tients giving greater weight to breathlessness than older patients. Conjoin t analysis appears to be a useful method for establishing the relative impo rtance of common symptoms.