A strategy for health assessment : the case of ulcerative colitis
Sammanfattning: The importance of a patient's experience of disease impact on daily life and well-being (health-related quality of life (HRQOL)) is broadly acknowledged. Scepticism still remains about how HRQOL should be measured and the usefulness of standardised HRQOL questionnaires in medical research and everyday clinical practice. The lack of definitions, and the unclear relationship between disease activity and HRQOL makes it difficult to interpret results.The main purpose of this thesis was to determine a strategy for health assessment that is useful in daily practise and meaningful for clinicians and patients. The results are based on measurements of HRQOL and disease activity in a total of 511 patients with ulcerative colitis.The first aim of this thesis was to identify the major health dimensions and study their relationship in order to determine a strategy for health assessment. Based on theoretical reasoning and the pattern of association between measures of different areas of health status, the health concept was arranged into two categories, disease activity and HRQOL. Disease activity was further divided into biological variables and symptoms, and HRQOL into fimction, disease-related worry, and general well being. There was a poor association between these health dimensions. Measurement of health status is therefore better understood if it is divided into and interpreted as separate dimensions. It is then possible to see which dimensions are impaired and changes that have occurred.The second aim was to evaluate two disease-specific HRQOL questionnaires, the RFIPC and the IBDQ in Swedish patients with ulcerative colitis. The RFIPC was found to be a valid, reliable and responsive measure of disease-related worry and concern. The IBDQ had external validity and was shown to be a reliable and responsive measure of HRQOL. There are however some concerns regarding the internal validity of the IBDQ. The use of an overall sum score was not supported and the original four IBDQ dimensions showed considerable overlap.The third aim was to study HRQOL in patients with ulcerative colitis and analyse the influence of disease-related and demographic factors. Patients in remission reported a health-related quality of life similar to that of a Swedish background population. Patients with an ongoing relapse showed a considerable impairment in all health dimensions except physical function compared to patients in remission. Besides the current disease activity, co-existing disease and female gender was found to weigh heavily on the HRQOL. These factors must therefore be taken into account when interpreting and comparing HRQOL results.The fourth aim was to develop and evaluate a new abbreviated measure of subjective health status. The construction of this new measure was based on a previously developed strategy where the health concept is divided into five main dimensions. Each of the dimensions for symptoms, fimction, disease-related worry and general well-being were covered by one item. This new four-item questionnaire, the Short Health Scale (SHS) was shown to be a valid and sensitive measure of subjective health status in ulcerative colitis.
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