The incidence of multimorbidity and patterns in accumulation of chronic conditions: A systematic review

Abstract

Multimorbidity, the presence of 1+ chronic condition in an individual, remains one of the greatest challenges to health on a global scale. Although the prevalence of multimorbidity has been well-established, its incidence is not fully understood. This systematic review determined the incidence of multimorbidity across the lifespan; the order in which chronic conditions accumulate to result in multimorbidity; and cataloged methods used to determine and report accumulation of chronic conditions resulting in multimorbidity. Studies were identified by searching MEDLINE, Embase, CINAHL, and Cochrane electronic databases. Two independent reviewers evaluated studies for inclusion and performed quality assessments. Of 36 included studies, there was high heterogeneity in study design and operational definitions of multimorbidity. Studies reporting incidence (n = 32) reported a median incidence rate of 30.7 per 1,000 person-years (IQR 39.5 per 1,000 person-years) and a median cumulative incidence of 2.8% (IQR 28.7%). Incidence was notably higher for persons with older age and 1+ chronic conditions at baseline. Studies reporting patterns in accumulation of chronic conditions (n = 5) reported hypertensive and heart diseases, and diabetes, as among the common starting conditions resulting in later multimorbidity. Methods used to discern patterns were highly heterogenous, ranging from the use of latent growth trajectories to divisive cluster analyses, and presentation using alluvial plots to cluster trajectories. Studies reporting the incidence of multimorbidity and patterns in accumulation of chronic conditions vary greatly in study designs and definitions used. To allow for more accurate estimations and comparison, studies must be transparent and consistent in operational definitions of multimorbidity applied.

Fifteen-year trajectories of multimorbidity and polypharmacy in Dutch primary care—A longitudinal analysis of age and sex patterns

“…Several aspects of our findings are noteworthy. Across a range of international settings, our findings largely agree with the results of other studies that multimorbidity prevalence increases with age [5,9,11,24]. The prevalence in the youngest female and male groups was 1.5% and 1.8% respectively in the first year, rising to 17.6% and 10.7% respectively at the end of the 15-year period.…”

“…The early development of multimorbidity may indicate earlier and longer cumulative exposure to risk factors that are common to many of the chronic health conditions. Risk factors that assault multiple body systems, such as obesity, chronic stress, and systemic inflammatory episodes, may lead to earlier multimorbidity, as may other factors including depressive disorder, cognitive decline [8] and weaknesses in social networks and family support [8,50] In addition, poor access to good quality health care and low SES may exacerbate and accelerate the development of multimorbidity [24,47].…”

“…Age is an important factor driving the development of polypharmacy and the accumulation of chronic health conditions accelerates the use of multiple drugs. Particular attention should be paid to polypharmacy because it is associated with many drug-related problems such as adverse drug events, drug-drug-interactions, medication non-adherence, functional decline, and cognitive impairment [10,24,25,33]. However, the clinical trajectory of a substantial portion of our patients accelerated and led to a further increase in polypharmacy across all age and sex groups.…”

The effect of disease onset chronology on mortality among patients with multimorbidity: A Danish nationwide register study

“…Mental health diagnoses are most harmful when they appear as the first diagnosis. Mental health conditions tend to appear at some point in the multimorbidity trajectory, with increasing risk with the number of somatic conditions 9 , 41 ; however, for some ethnic and younger age groups, depression is often the starting diagnosis. 33 Furthermore, there is a relation between mental health conditions and the development of later somatic conditions.…”

Incidence and predictors of multimorbidity among older adults in Korea: a 10-year cohort study

“…A number of studies have investigated the prevalence and incidence of multimorbidity in various populations [10][11][12][13][14]. In a systematic review, the incidence rate of multimorbidity has ranged from 2.56 per 1000 personyears to 329 per 1000 person-years [15]. As part of the prevention efforts, a number of studies have focused on identifying key determinants and high-risk populations of multimorbidity across different conditions and age groups.…”