Improving the measurement of quality of life in people with multiple long term conditions

Problem

The growing number of people living with multiple long term conditions (MLTC) poses a major challenge in healthcare, but the evidence base for interventions in patients with MLTC is limited, with many studies failing to demonstrate improvement in quality of life (QoL) using outcome measures such as EQ5D and SF36. However, these generic measures were not developed for people with MLTC and their psychometric adequacy in multimorbidity research is questionable. The need for new QoL measures designed for use in people with MLTC has been identified as a research priority. In response to this, researchers at the University of Copenhagen recently developed the Multimorbidity Questionnaire (MMQ). The present study involved the translation and revalidation of the MMQ in English.

Approach

The Danish-language MMQ underwent preliminary translation into English by a panel of bilingual experts in Spring 2023. Following this, a PPI focus group was held in which six participants, with a range of socioeconomic backgrounds, reviewed and refined the questionnaire line-by-line in order to adapt it semantically for use in a UK context. Six individual cognitive interviews were then held with participants with diverse experiences of MLTC. Interviews employed a think-aloud approach to assess content validity. Following this, MMQ was used in a postal survey of approximately 600 patients with MLTC, sampled randomly from 12 GP practices in Lothian. EQ5D and ICE-CAP (generic measures of QoL) were included alongside MMQ in order to assess concurrent validity. The survey also included feedback items assessing acceptability and feasibility.

Findings

Through six cognitive interviews, MMQ demonstrated strong content validity, with comprehensive coverage, high relevance and strong understandability. Three items underwent minor rewording after the first four interviews, to improve clarity. While some items lacked direct relevance to interviewees, they nevertheless demonstrated strong face validity, and given the strength of the underpinning qualitative work, these items were retained. Broadly, it was felt that MMQ’s acceptability would be improved by shortening the measure. The survey was sent to 2370 patients, and 587 responses were received (25% response rate). At the time of writing, data analysis is currently underway. This involves Rasch modelling, considered the strictest form of Modern Test Theory psychometrics. Planned analyses include unidimensionality, internal reliability, measurement invariance, known-group validity, and concurrent validity. Feedback items and completion rates will also be analysed to assess acceptability and feasibility. Complete analysis is expected by April 2024.

Consequences

While full results are not yet available, this is a study with a robust design which addresses an urgent priority within MLTC research. Validation of MMQ will provide a much needed tool for measuring QoL in people with MLTC. Rasch analysis will also provide a framework for future work to improve MMQ’s acceptability by shortening it to its most useful items.