The construction and validation of a health-related quality of life measure for women with endometriosis

[摘要] ENGLISH SUMMARY: The purpose of this study was to construct and validate a health-related quality of life (HRQOL) measure for patients with endometriosis. The study employed an exploratory, sequential mixed methods research design, consisting of a qualitative phase, followed by a quantitative phase. The study consisted of three aims.The first aim was to describe and understand the QOL-related experiences of women with endometriosis. This qualitative phase of the study involved in-depth, semi-structured interviews with 25 women diagnosed with endometriosis. I recorded and transcribed the interviews. I used thematic analysis to code the data and identify themes. Eleven themes emerged from the data, namely psychological functioning, sexual functioning, financial impact and considerations, healthcare and medical treatment, reproductive functioning, information and knowledge, interpersonal functioning, menstrual characteristics, occupational functioning, somatic features and physical functioning.The second aim of the study was to construct items for the instrument based on data collected during the first phase. The initial item pool consisted of 314 items. I then consulted with two experts in psychometry, who provided feedback relating to the clarity, conciseness, wording and ambiguity of items. This process resulted a reduced pool of 184 items.I asked five endometriosis experts to review the items in terms of relevance. Items that the experts regarded as highly relevant were retained in the measure and items that were not regarded as highly relevant were removed from the measure. The review resulted in the retention of 64 items. I piloted these items among seven women with endometriosis in order to assess the readability of the items. The final aim of the study was to determine the test reliability, validity and factor structure of the measure. This formed the quantitative component of the study. I administered the 64-item HRQOL measure, Endometriosis Health Profile 30, Short Form Health Survey World Health Organization Quality of Life Brief scale and the Beck Depression Inventory to 203 patients with endometriosis. I conducted an item analysis and removed 16 items that displayed corrected item total correlations below .35. I then conducted an exploratory factor analysis (EFA) on the remaining 48 in order to establish the factor structure of the measure. The factor analysis identified thirteen items that either cross-loaded on more than one factor or that did not significantly load on any factor. These items were removed. The remaining 35 items produced an eight-dimension factor structure. A second EFA produced the same factor structure. I named the measure the Stellenbosch Endometriosis Quality of life (SEQOL) measure and the named the dimensions as follows: (1) Psychological well-being; (2) Income; (3) Sexual functioning and romantic relationships; (4) Reproductive functioning; (5) Vitality; (6) Occupational functioning; (7) Menstrual characteristics and (8) Support. The SEQOL and its subscales demonstrated excellent internal consistency reliability. The SEQOL produced a Cronbach's α of .92 and the Cronbach's α for the subscales ranged from .72 to .88. Correlations between scores on SEQOL, its subscales and other measures indicated promising validity. The initial validation indicates that the SEQOL may be a useful assessment of HRQOL in women with endometriosis, both in research and clinical practice.

[发布机构] Stellenbosch University