EFFECT OF THE METHOD OF ADMINISTRATION, MAIL OR TELEPHONE, ON THE VALIDITY AND RELIABILITY OF A RESPIRATORY HEALTH QUESTIONNAIRE - THE SPANISH CENTERS OF THE EUROPEAN ASTHMA STUDY

The European Community Respiratory Health Survey (ECRHS), a multinatio nal survey, assesses and compares the prevalence of asthma among subje cts, aged 20 to 44, in several European areas. In Spain, some particip ating centers have used mail and telephone as methods of questionnaire administration. The objective of the present study was to determine w hether the validity and reliability of the questionnaire differed by m ethod of administration. Reliability of the questionnaire was measured with the kappa index and the odds ratio of agreement, and validity wi th the sensitivity and specificity. This study found differences in th e reliability of the questionnaires although these differences were mo re related to the questions themselves than to the method of administr ation. Among men, but not women, mailed questionnaires were more sensi tive and telephone questionnaires more specific. We hypothesize that t hese differences in validity were due to the self-selection to more se vere symptomatic subjects replying earlier and therefore to the mailed questionnaire. Combining different methods of administration was usef ul as it increased participation and was an adequate procedure to obta in information of good quality. (C) 1998 Elsevier Science Inc.