Multimorbidity and quality of life at mid-life: A systematic review of general population studies

Highlights

• Eight articles were identified from four databases. Multimorbidity is consistently associated with poorer HrQoL at mid-life.

• Two cross-sectional studies found adults with multimorbidity at early mid-life reported poorer HrQoL than those at late mid-life, while another found the reverse.

• Two distinct disease clusters were identified at mid-life: mental health conditions, cardiovascular disease (CVD).

• Those in mental health clusters reported poorer HrQoL than those in CVD clusters at mid-life.

• Future research using weighted disease severity index and multimorbidity trajectories based on longitudinal data is needed.

Abstract

There is substantial multimorbidity at mid-life but little is known about the strength of evidence on multimorbidity and health-related quality of life (HrQoL) at mid-life. This review addresses this gap, focusing on studies of the general population. PubMed, Web of Science, Embase and APA PsycNET databases were screened on 6 March 2017 for original research on multimorbidity and HrQoL in adults aged 40–65 years from the general population. Studies focused on index conditions, using single-item HrQoL measures, unlikely to represent the general population (e.g. primary care), and papers that were not in the English language were excluded. A narrative synthesis was presented due to heterogeneity in the measurement of multimorbidity. Of the 2557 articles, 83 underwent full text screening and 8 were included in the review. Included studies were of moderate to high quality and no exclusions were made on the basis of quality or bias. Multimorbidity was associated with poorer HrQoL at mid-life. Two cross-sectional studies found that adults with multimorbidity at early mid-life reported poorer HrQoL than adults with multimorbidity at late mid-life, while another found the reverse. Two distinct disease clusters were identified: mental health conditions and cardiovascular disease (CVD). Those in the mental health cluster reported poorer HrQoL than those in the CVD cluster, women more so than men. Limitations of the selected studies include lack of longitudinal evidence, use of self-reported conditions and no assessment of disease severity. Multimorbidity is associated with poor HrQoL at mid-life at the population level, with some evidence of differences in association with age and disease cluster and sparse evidence on sex differences. Longitudinal research using a weighted disease severity index and multimorbidity trajectories is needed to strengthen the evidence base.

Introduction

Multimorbidity, the co-occurrence of at least two health conditions in an individual [[1], [2], [3], [4], [5], [6]], is an increasing health problem. It is brought about by population aging, unhealthy lifestyle habits, emerging chronic conditions, reduced mortality from improved medical care and technologies, and earlier detection and treatment of conditions [7]. Globally, multimorbidity prevalence is estimated to be between 3.5% and 100% [8]. The large variation is estimates observed is driven by differences definition and measurement of multimorbidity, population setting, participant age range, and country income levels [9]. Despite this, there is consensus that multimorbidity represents significant and growing burden to society [7]. Increased multimorbidity burden can lead to greater complexity in patient health management, reduced health related quality of life (HrQoL), and increased health care use and costs [[10], [11], [12]].

While multimorbidity is common in older adults, studies have shown that those under 65 years old also experience a substantial multimorbidity burden [[1], [13], [14], [15]]. A recent systematic review highlighted a ‘S’ shape curve of multimorbidity prevalence with age [2], where prevalence increased steeply at mid-life, and plateaued in those age 75 years and above. The onset of conditions at mid-life may affect HrQoL. Previous systematic reviews on multimorbidity and HrQoL have focused on primary care populations[[12], [16]] or older adults (age 65+) [17] and have shown that multimorbidity is negatively associated with HrQoL in these populations. However little is known on the strength of evidence on multimorbidity and HrQoL at mid-life or at the general population level. Given the substantially higher prevalence and disease burden of multimorbidity in primary care compared to the general populations [18], there need for synthesis of evidence at a population level to assist in health service planning.

It is unclear whether multimorbidity rates differ between males and females. The prevalence of multimorbidity is slightly higher in females compared to males, however findings are inconsistent [[7], [14], [19]]. Some patterns of multimorbidity differ between males and females [19]. For example, depressive symptoms is more common in females while psychiatric and substance abuse is more common in young males [19]. These sex differences in prevalence and patterns of multimorbidity coupled with the onset of conditions at midlife may modify the association between multimorbidity and HrQoL.

This review aims to quantify the relationship between multimorbidity and HrQoL at mid-life, at the population level. It will clarify whether the relationship is consistent between sexes, for different methods to measure multimorbidity, and between preference weighted and non-preference weighted HrQoL instruments.