Effectiveness of routine self monitoring of peak flow in patients with asthma. Grampian Asthma Study of Integrated Care (GRASSIC).

OBJECTIVE--To evaluate the effectiveness of routine self monitoring of peak flow for asthma outpatients. DESIGN--Pragmatic randomised trial. SETTING--Hospital outpatient clinics and general practices in north east Scotland. MAIN OUTCOME MEASURES--Use of bronchodilators and inhaled and oral steroids; number of general practice consultations and hospital admissions for asthma; sleep disturbance and other restrictions on normal activity; psychological aspects of health including perceived control of asthma. RESULTS--After one year there were no significant differences between patients randomised between self monitoring of peak flow and conventional monitoring. However, those given a peak flow meter recorded an increase in general practice consultations that was nearly significant. Among patients whose asthma was judged on entry to be more severe, those allocated to self monitoring used more than twice as many oral steroids (2.2; 95% confidence interval 1.1 to 4.6). Patients who already possessed a peak flow meter at the start of the study recorded higher morbidity over the course of the year than those eligible for randomisation. CONCLUSION--Prescribing peak flow meters and giving self management guidelines to all asthma patients is unlikely to improve mortality or morbidity. Patients whose asthma is severe may benefit from such an intervention.