NEAR-FATAL ASTHMA ATTACKS - THE RELIABILITY OF DESCRIPTIVE INFORMATION COLLECTED FROM CLOSE ACQUAINTANCES

Background-The reliability of information collected from close acquain tances of the deceased in studies on mortality from asthma has not bee n assessed. As part of a South Australian asthma mortality study, leve ls of agreement for information obtained directly from cases-that is, cases who had experienced near fatal asthma attacks-were compared with corresponding information concerning these cases obtained independent ly from close acquaintances. Methods-The first 51 subjects presenting from the outset of the main study to hospital accident and emergency d epartments with near fatal asthma attacks were included to gain an ear ly assessment of the reliability of responses. The level of agreement between self reported information and that obtained from close acquain tances was compared by means of a kappa statistic or intraclass correl ation coefficient, depending on the measurement scale. Both score one for complete agreement and zero when there is no agreement. Results-Hi gh levels of agreement were found for questions relating to use of hos pital services, with agreement levels ranging from 0.92 for visits in the past month to accident and emergency departments, to 0.86 for prio r hospital admissions and 0-78 for prior need for assisted ventilation . Levels of agreement for drug treatment ranged from 1-00 for use of b eta agonists to 0.64 for corticosteroid use, and to a low 0.24 for use of sodium cromoglycate. There was moderate agreement for histories of regular use of over the counter medications without a medical consult ation (0.57). Psychiatric characteristics showed moderate levels of ag reement, with values of 0.44 for personal history of psychiatric consu ltations and 0.50 for denial score. Agreement scores were 0-66 for doc tor visits in the past month, 0-66 for limitations in daily activities , 0.76 for loss of work days in the past month, 0.59 for severity of a sthma, and 0.55 for frequency of asthma attacks in the past month. Poo rer agreement scores were found for trends in asthma symptoms (0.21) a nd frequency of symptoms during the past three years (0-12). Sleep dis turbance was also associated with a low agreement score (0.25). Conclu sions-The more visible the asthma manifestation, and the more recent t he period to which it applies, the more reliable is the information pr ovided by close acquaintances. These factors need to be taken into acc ount when using information from close acquaintances in asthma mortali ty studies.