Abstract
This thesis shows the results and patient characteristics of three studies. One study was part of the Dutch Mite Avoidance Study (DUMAS): Effectiveness and effect modification of encasings in house dust mite allergy. The two other studies were two different studies with asthmatic patients recruited from and performed at the
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asthma centre Heideheuvel. Patient recruitment of the Heideheuvel study took place in the same geographical region in the period 1995-1997; the DUMAS study in 1997 and 1998.
In the DUMAS study patients were selected by using questionnaires where particular atopical core questions were addressed, together with a positive intradermal test or skin prick test for house dust mite. Patients were diagnosed as having reported AR, AA and/or AD on basis of this questionnaire. Then patients were randomised and stratified by age and recruiting centre. After randomisation patients were tested for AA with lung function tests (methacholine, adenosine, histamine); for AR, using nasal provocation tests with HDM and the nasal-score2; and for AD, using the LSS for symptom grading and disease extent together with tests for allergen load and immunological and quality of life (QoL) variables. A difference in diagnoses was made by using questionnaires solely (reported diagnoses) and using questionnaires in combinations with clinical tests (clinical diagnoses). A difference between reported and clinical diagnoses was found in 84 out of 325 patients (25.8 %)(Chapter 2). There was a reported atopical comorbidity of 235 out of 325 patients (72.3 %) and a clinical atopical comorbidity of 177 in 325 patients (54.4 %).
Chapters 3, 4 and 5 show the effects of encasings on clinical, immunological and QoL variables. There was a lack of improvement of AD and AA in the active treatment groups despite a significant decrease in Der p1 and Der p1 + f1 exposure.
QoL becomes an important issue in evaluating effects of treatment in patients with chronic diseases. Several disease specific and generic questionnaires have been developed. Disease specific questionnaires assess the severity of particular disease specific (AA and AD) symptoms on patient’s life while generic questionnaires addresses the general “well being”. Looking at the prevalence of atopic comorbidity within the selected populations, usage of both kinds of questionnaires is recommended (Chapter 6)
Lack of clinical effect of encasings on AA and AD resulted in a lack in improvement of QoL between the placebo and active treatment groups as measured with disease specific and generic questionnaires in both study populations (Chapter 5, 6, 7, 8). Interestingly, within the AD population the disease specific QCSD and the generic SF-36 questionnaire revealed body-site specific effects of trunk and arms on QoL (Chapter 7, 8)
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