Multimorbidity and quality of life at mid-life: A systematic review of general population studies
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.
Section snippets
Protocol and registration
The corresponding review protocol is registered at PROSPERO (CRD42017056911).
Study selection
This review focused on original quantitative epidemiological research that evaluated the association between multimorbidity and HrQoL in mid-age adults (aged 40–65 years) in the general population. We also included cohort or cross-sectional studies on adults where separate estimates of multimorbidity and HrQoL were available for adults aged 40–65 years. For the purpose of this review, multimorbidity is defined as “
Study selection: overall description of screening/assessment process
A total of 3698 articles were identified from the four databases, and 2557 were screened based on title and abstract (Fig. 1). After full text screening and quality and risk of bias assessment, 8 articles were included in the review, of which one article was identified from the reference list of an included article. All articles included in synthesis were moderate to high quality based on the Fortin and NOS assessments (Table 1). No articles were excluded on the basis of quality or risk of
Discussion
This review highlights that recent data on multimorbidity and HrQoL at mid-life, using studies based on the general population is sparse, limited to cross-sectional research, and with substantial heterogeneity in the measurement and reporting of multimorbidity [4]. There were consistent findings across adult and mid-life studies that multimorbidity was associated with poorer HrQoL at mid-life. While there has been no review of the literature on multimorbidity and HrQoL focused at mid-life to
Conclusion
This review identified eight relevant studies and found consistently, multimorbidity was associated with poorer HrQoL at mid-life. There was some cross-sectional evidence of a difference in this association between early and late mid-life, and disease cluster, however more research is needed for conclusive findings. Given that the onset of morbidity at mid-life can affect HrQoL, research from longitudinal studies which measure multimorbidity using indices that incorporate severity of disease
Contributors
Jeeva Kanesarajah performed the literature review, designed the search strategy, screened titles and abstracts and full text, determined quality of the articles and performed the data extraction, and drafted the manuscript.
Michael Waller determined quality of the articles
All authors contributed to study conception and designed the review, participated in data synthesis/analysis and data interpretation. All authors contributed to the critical revision of the manuscript, and saw and approved the
Conflict of interest
The authors declare that they have no conflict of interest.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Jeeva Kanesarajah is funded by the Australian Government Research Training Program. Gita D. Mishra is supported by NHMRC Principal Research Fellowship.
Provenance and peer review
This article has undergone peer review.
Acknowledgements
Thanks to Scott McIntyre, Xiaolin Xu and Louise Wilson for their valuable advice during the systematic review process.
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