# Analysing the impact of complex multimorbidity on health-related quality of life

## TL;DR

This study shows that complex multimorbidity significantly reduces health-related quality of life across multiple dimensions, especially pain and mental health.

## Contribution

The paper provides novel estimates of the impact of complex multimorbidity on health utility using the EQ-5D-5L instrument.

## Key findings

- Complex multimorbidity is associated with a health utility loss of −0.506 compared to those without serious illness.
- The greatest impact of multimorbidity is observed in pain/discomfort and anxiety/depression dimensions.
- Interventions delaying multimorbidity onset could significantly improve health-related quality of life.

## Abstract

This paper presents independent associations between complex multimorbidity and health-related quality of life using the EQ-5D-5L instruments. Identifying the decrements in utility associated with complex multimorbidity is of value for economic evaluation and health technology assessment.

Data from the population normative dataset from the Irish EQ-5D-5L study were combined with baseline data from the SPPiRE (Supporting Prescribing in Older Adults with Multimorbidity in Irish Primary Care) randomised controlled trial. The trial included an Irish cohort aged 65+ with complex multimorbidity. For the analysis, the estimation sample consisted of 364 individuals from the SPPiRE complex multimorbidity sample, along with 116 individuals aged 65+ from the general population who did not report having any serious illness. A multivariate ordered probit regression model was used to estimate the independent associations between complex multimorbidity and the five EQ-5D-5L dimensions.

Complex multimorbidity was independently associated with a lower probability of reporting no problems for all five EQ-5D-5L dimensions, and a higher probability of reporting the most extreme response for all five dimensions. The loss in health utility associated with complex multimorbidity was estimated to be − 0.506 (95% CI − 0.567, − 0.445) relative to those aged 65 years and over with no serious illness. The negative health impact was most pronounced for pain/discomfort and anxiety/depression.

This study reported the associative impacts of complex multimorbidity for all EQ-5D-5L dimensions and for health utility overall. The findings highlight the potential impact on health-related quality of life of interventions that can prevent or delay the onset and progression of multimorbidity.

The online version contains supplementary material available at 10.1007/s11136-025-04120-9.

Multimorbidity, is the co-existence of two or more chronic conditions in an individual, including physical and mental health conditions, non-communicable diseases, and long-term infectious diseases. It is a growing concern for policy makers for several reasons. Firstly, it can have a significant impact on the individual, in terms of their quality of life, psychological well-being and physical function. In addition, it has an impact on the health system, as individuals with multimorbidity tend to require more complex care, involving multiple medical specialties. In this context, this paper provides important estimates of the impact of multimorbidity on health-related quality of life. We find that having multimorbidity leads to a significant decrease in health-related quality of life across five dimensions - mobility, self-care, usual activities, pain/discomfort and anxiety/depression. This means that if we can develop new models of care that delay or prevent the onset and progression of multimorbidity, it is likely to result in significant health benefits for the individual, and by extension, the health system.

The online version contains supplementary material available at 10.1007/s11136-025-04120-9.