Impact of multimorbidity and complex multimorbidity on mortality among older Australians aged 45 years and over: a large population-based record linkage study

Abstract

ObjectivesMultimorbidity (MM, co-occurrence of two or more chronic conditions) and complex multimorbidity (CMM, three or more chronic conditions affecting three or more different body systems) are used in the assessment of complex healthcare needs and their impact on health outcomes. However, little is known about the impacts of MM and CMM on mortality in Australia.DesignCommunity-based prospective cohort study.SettingNew South Wales, Australia.ParticipantsPeople aged 45 years and over who completed the baseline survey of the 45 and Up Study.MeasuresBaseline survey data from the 45 and Up Study were linked with deaths registry data. Deaths that occurred within 8 years from the baseline survey date were the study outcome. Eleven self-reported chronic conditions (cancer, heart disease, diabetes, stroke, Parkinson’s disease, depression/anxiety, asthma, allergic rhinitis, hypertension, thrombosis and musculoskeletal conditions) from the baseline survey were included in the MM and CMM classifications. Cox proportional hazard models were used to estimate adjusted and unadjusted 8-year mortality hazard ratios (HRs).ResultsOf 251 689 people (53% female and 54% aged ≥60 years) in the cohort, 111 084 (44.1%) were classified as having MM and 39 478 (15.7%) as having CMM. During the 8-year follow-up, there were 25 891 deaths. Cancer (34.7%) was the most prevalent chronic condition and the cardiovascular system (50.9%) was the body system most affected by a chronic condition. MM and CMM were associated with a 37% (adjusted HR 1.36, 95% CI 1.32 to 1.40) and a 22% (adjusted HR 1.22, 95% CI 1.18 to 1.25) increased risk of death, respectively. The relative impact of MM and CMM on mortality decreased as age increased.ConclusionMM and CMM were common in older Australian adults; and MM was a better predictor of all-cause mortality risk than CMM. Higher mortality risk in those aged 45–59 years indicates tailored, person-centred integrated care interventions and better access to holistic healthcare are needed for this age group.

Impact of multimorbidity and complex multimorbidity on healthcare utilisation in older Australian adults aged 45 years or more: a large population-based cross-sectional data linkage study

“…45 Also, a larger proportion of younger participants had no chronic conditions (among those without MM or CMM) than older participants (see figure 2 ), adding to the contrast in outcomes between those with MM or CMM and those without when outcomes were stratified by age. Notably, and similar to our findings in this and our previous study, 31 Meng et al have shown greater impact of MM (or ‘high need, high cost’ in their analysis) on service use and mortality among middle-aged (40–64 years) versus older (≥65 years) adults (adjusted HR: 4.41 vs 2.44 for potentially preventable hospitalisations; 2.09 vs 1.75 for any ED visit; 7.20 vs 3.35 for mortality). 46 We recommend targeting interventions towards people with MM and/or CMM in the youngest group (45–59 years) as that is where mortality risk is greatest (from our previous paper), 31 to try to prevent acquisition of further comorbidities and to try to reduce the impact of MM and CMM on healthcare utilisation in the longer term.…”

“…Notably, and similar to our findings in this and our previous study, 31 Meng et al have shown greater impact of MM (or ‘high need, high cost’ in their analysis) on service use and mortality among middle-aged (40–64 years) versus older (≥65 years) adults (adjusted HR: 4.41 vs 2.44 for potentially preventable hospitalisations; 2.09 vs 1.75 for any ED visit; 7.20 vs 3.35 for mortality). 46 We recommend targeting interventions towards people with MM and/or CMM in the youngest group (45–59 years) as that is where mortality risk is greatest (from our previous paper), 31 to try to prevent acquisition of further comorbidities and to try to reduce the impact of MM and CMM on healthcare utilisation in the longer term. In older age groups, broader population-based strategies could be considered instead of targeted interventions designed for people with MM and CMM.…”

“…We checked for effect modification for age groups by adding an interaction term into the Poisson model. We conducted subgroup analysis stratified by three age categories (youngest group (45–59 years), middle group (60–74 years) and oldest group (≥75 years)) to assess any differential effect of MM or CMM according to age as was observed in our previous study 31. We set 0.05 as the significance level for all statistical tests and used R V.3.6.3 software (R Foundation, Vienna, Austria) for data analysis and SAS V.9.4 (SAS Institute, Cary, North Carolina, USA) for data management.…”

“… 23 26 Internationally, CMM has been found to be associated with increased risk of mortality 27 28 and healthcare utilisation. 29 30 Though there has been limited evaluation of the impact of CMM on mortality in Australia, 31 to our knowledge, no studies have evaluated the impact of CMM on healthcare utilisation in Australia or evaluated whether MM or CMM has greater impact on service use. Hence, the objective of our study was to measure and compare the impact of MM and CMM on healthcare utilisation in a large community-dwelling population of Australian adults aged ≥45 years.…”

Improving life expectancy with primary health care

“…As the population ages, the burden of multimorbidity (defined as two or more chronic conditions) grows, a process that is unfolding in both Aotearoa New Zealand (NZ) 1 and Australia. 2 In addition to the need for continuing health care and the risk of complications, multimorbidity can shorten life expectancy. The mortality burden, however, is not shared equally, but falls most heavily on the socioeconomically disadvantaged and several ethnic groups, notably Māori and Pacific peoples in NZ 1 and Aboriginal and Torres Strait Islander peoples in Australia.…”