Population ageing is one of the most significant demographic transformations of the present era. The number of individuals aged 60 years and above worldwide is projected to rise from 901 million in 2011 to over 2.1 billion by 2050, with the proportion of the global population in this age group increasing from approximately 12% to 22% over the same period (1,2). India mirrors this global trend, with the proportion of older adults projected to rise from 8% in 2011 to 19% by 2050, and roughly a third of the country's population expected to be aged 60 years or above by the end of the century (2). This demographic shift carries profound implications for healthcare systems, since older adults are disproportionately affected by chronic, non-communicable diseases, which collectively account for an estimated 71% of all deaths globally, amounting to approximately 41 million deaths annually (3).

A defining clinical feature of ageing populations is multimorbidity, generally defined as the coexistence of two or more chronic health conditions within the same individual (4). Unlike comorbidity, which classically refers to additional conditions in relation to an index disease, multimorbidity considers the overall burden of chronic disease without designating any single condition as primary, and is now recognised as a more clinically meaningful construct for understanding the health needs of older adults (4,5). The reported prevalence of multimorbidity among elderly populations varies considerably across studies and settings, ranging from 24% to 83%, reflecting differences in study design, the number and type of conditions assessed, and the characteristics of the population studied (5,6).

Data from the Longitudinal Ageing Study in India (LASI), the country's largest nationally representative survey of older adults, indicate that multimorbidity prevalence among those aged 60 years and above ranges from approximately 30% to over 50% depending on the analytic approach and case definition used, with hypertension, arthritis, and chronic lung disease emerging as among the most prevalent individual conditions (7,8). The same data consistently demonstrate that multimorbidity increases steeply with advancing age, rising from approximately 45% in those aged 40 years and above to over 74% in those aged above 80 years, and is generally more prevalent among women, urban residents, and those with greater household wealth, reflecting both biological and healthcare-access-related determinants (8,9). A systematic review and meta-analysis of risk factors for multimorbidity among older Indians similarly confirmed significantly higher odds of multimorbidity in those aged 70 years and above compared with the 60–69 year age group, in women compared with men, and in those who were widowed, divorced, or economically dependent compared with their counterparts (6).

Hospital-based studies focusing specifically on elderly patients attending tertiary care have provided additional granularity regarding the specific pattern of comorbidity clustering in this population. A cross-sectional study of geriatric outpatients in a South Indian tertiary hospital found that 66.17% of patients had multimorbidity, with a mean of 2.39 chronic conditions per patient, and identified hypertension and type 2 diabetes mellitus as the most prevalent conditions overall, with distinct gender-specific patterns in comorbidity clustering identified through hierarchical cluster analysis (10). Similarly, a study of elderly patients attending a tertiary care wellness centre found that type 2 diabetes, musculoskeletal disorders, and genitourinary disorders were the most prevalent morbidities, collectively affecting half of the elderly population studied, with multimorbidity shown to have a significant adverse impact on quality of life across physical, psychological, social, and environmental domains (11). Beyond simple prevalence, factor-analytic approaches applied to large claims-based and hospital-based cohorts of older adults have identified recurring, non-random clusters of comorbidity — broadly described as cardiovascular, induced-dependency, falls, and osteoarticular patterns — suggesting that certain conditions cluster together more than would be expected by chance and may share common underlying pathophysiological or functional pathways (12,13).

Despite this expanding evidence base, considerable variation persists in the reported prevalence and pattern of comorbidities across different healthcare settings, populations, and geographic regions, and continued local characterisation remains valuable both for healthcare planning and for tailoring comprehensive geriatric assessment protocols to the population actually being served. The present study was therefore undertaken to determine the pattern, prevalence, and burden of comorbidities among elderly patients attending a tertiary care hospital, and to examine variation in multimorbidity burden according to age and sex.

Study Design and Setting This cross-sectional observational study was conducted in the Department of Geriatric Medicine at a tertiary care teaching hospital over a period of 12 months, following approval from the Institutional Ethics Committee. Written informed consent was obtained from all participants, or from a caregiver in the case of patients with cognitive impairment, prior to enrolment. Study Population All patients aged 60 years and above attending the outpatient department or admitted to the inpatient wards of the hospital during the study period were screened for eligibility, and patients were enrolled using a consecutive, non-probability sampling technique until the target sample size was reached. A total of 400 patients fulfilling the eligibility criteria were enrolled. Patients who were critically ill or haemodynamically unstable at the time of assessment, those unable to provide a reliable history even with caregiver assistance, and those who declined to participate or did not provide consent were excluded. Data Collection A structured proforma was used to collect demographic information including age, sex, residence (urban or rural), educational status, employment status, and living arrangement (living alone versus with family). A detailed history of all pre-existing chronic medical conditions was obtained from each patient, supplemented by review of available medical records, prescriptions, and previous investigation reports where available. All patients underwent a comprehensive clinical examination, including measurement of blood pressure, pulse, anthropometric parameters, and a basic neurological and musculoskeletal assessment. Investigations and Case Definitions Relevant laboratory investigations, including fasting and postprandial blood glucose, glycated haemoglobin, renal function tests, complete blood count, thyroid function tests, lipid profile, and electrocardiography, were performed in all patients to confirm or newly detect chronic conditions where clinically indicated. Standard diagnostic criteria were used for each condition: hypertension was defined per current guideline blood pressure thresholds or current use of antihypertensive medication; type 2 diabetes mellitus was defined per American Diabetes Association criteria or current use of antidiabetic medication; and other conditions (osteoarthritis, chronic obstructive pulmonary disease, ischaemic heart disease, chronic kidney disease, hypothyroidism, cataract, stroke, depression, dyslipidaemia, and anaemia) were diagnosed using standard clinical, biochemical, or radiological criteria as appropriate, with specialist consultation sought where necessary. Multimorbidity was defined as the presence of two or more of the above chronic conditions in the same individual, in keeping with the most widely used definition in the literature. Statistical Analysis Data were entered into a structured spreadsheet and analysed using SPSS software. Continuous variables were expressed as mean ± standard deviation, and categorical variables as frequencies and percentages. The prevalence of multimorbidity was compared across age groups and between sexes using the chi-square test, with a p-value of less than 0.05 considered statistically significant. The most frequently occurring comorbidity combinations were identified by cross-tabulating individual conditions and ranking combinations by frequency of co-occurrence.

A total of 400 elderly patients were enrolled in the study. The demographic and clinical characteristics of the study population are summarised in Table 1.

Table 1. Demographic and clinical characteristics of the study population (N = 400)

The mean age of the study population was 68.9 ± 6.8 years, with the majority of patients in the 60–69 year age group (53.0%). There was a relatively balanced sex distribution, with a slight male predominance (53.0%). Most patients resided in urban areas (62.0%), and 11.5% of patients lived alone, a factor previously associated with increased vulnerability to chronic disease burden in this age group.

Table 2. Overall burden of multimorbidity among the study population

Multimorbidity, defined as the presence of two or more chronic comorbidities, was present in 63.0% of the study population, while 23.0% had a single comorbidity and only 14.0% had no diagnosed chronic comorbidity at the time of assessment. Among patients with multimorbidity, the majority had two (27.0% of the total cohort) or three (21.0%) comorbid conditions, while 15.0% of the overall cohort had four or more comorbidities. The mean number of comorbidities per patient across the entire study population was 2.4 ± 1.6.

Table 3. Prevalence of individual comorbid conditions among the study population

Hypertension was the single most prevalent comorbidity, present in 58.0% of patients, followed by type 2 diabetes mellitus (41.0%) and osteoarthritis or other musculoskeletal disorders (32.0%). Chronic obstructive pulmonary disease (21.0%) and ischaemic heart disease (19.0%) were the next most common conditions, reflecting the substantial burden of both metabolic and cardiopulmonary disease in this population. Among male patients specifically, benign prostatic hyperplasia was present in 19.8%. Mental health conditions, specifically depression or anxiety disorder, were identified in 9.0% of patients, a proportion that may under-represent the true burden given the recognised under-reporting of psychological symptoms in this age group.

Table 4. Most frequently occurring comorbidity combinations

The most common two-condition comorbidity combination was hypertension with type 2 diabetes mellitus, present in 19.5% of the overall study population, followed by hypertension with osteoarthritis (13.0%). Among three-condition combinations, hypertension, dyslipidaemia, and ischaemic heart disease together were present in 8.5% of patients, while hypertension, type 2 diabetes mellitus, and chronic kidney disease co-occurred in 6.5% of patients, reflecting a recognisable cardio-renal-metabolic cluster.

Table 5a. Prevalence of multimorbidity by age group

Table 5b. Prevalence of multimorbidity by sex

Multimorbidity prevalence increased significantly with advancing age, from 52.8% in the 60–69 year age group to 69.6% in the 70–79 year age group and 88.0% in those aged 80 years and above (p<0.001), demonstrating a clear and consistent age-related gradient. Multimorbidity was also significantly more prevalent among female patients (71.3%) compared with male patients (55.7%, p<0.001), a pattern consistent with previously reported sex differences in chronic disease burden among older adults.

The present study demonstrates a high burden of multimorbidity among elderly patients attending a tertiary care hospital, with 63.0% of patients having two or more chronic comorbid conditions and a mean of 2.4 ± 1.6 comorbidities per patient. These findings are consistent with the wide range of multimorbidity prevalence reported in the literature, which spans from 24% to 83% depending on study setting, case definition, and the number of conditions assessed, and align closely with hospital-based estimates from comparable South Asian tertiary care populations (5,6). Our finding that hypertension (58.0%) and type 2 diabetes mellitus (41.0%) were the two most prevalent individual comorbidities, and that their combination was the single most common comorbidity pairing (19.5%), closely mirrors findings from a cross-sectional study of geriatric outpatients in a South Indian tertiary hospital, which similarly identified hypertension and type 2 diabetes mellitus as the most prevalent conditions among 541 older adults, with an overall multimorbidity prevalence of 66.17% and a mean of 2.39 chronic conditions per patient — figures that are almost numerically identical to our own (10). This consistency across independent hospital-based cohorts reinforces the central position of cardiometabolic disease as the dominant driver of multimorbidity in ageing populations, particularly in the South Asian context. Data from the Longitudinal Ageing Study in India have similarly identified hypertension as the most prevalent single condition among older Indians, with chronic lung disease and stroke more prevalent in men and arthritis and thyroid disorders more prevalent in women, a pattern of sex-specific clustering that is broadly compatible with our own observation of significantly higher overall multimorbidity prevalence among women (71.3%) compared with men (55.7%) in our cohort (8,9). This female excess in multimorbidity burden has been attributed in prior work to a combination of biological factors, such as differential susceptibility to musculoskeletal and thyroid disease, and social factors, including lower educational attainment, economic dependency, and longer life expectancy with accumulated chronic disease exposure, all of which have been independently associated with higher odds of multimorbidity in systematic reviews of Indian elderly populations (6). The steep age-related gradient in multimorbidity prevalence observed in our study, rising from 52.8% in the 60–69 year age group to 88.0% in those aged 80 years and above, is consistent with national-level Indian data showing multimorbidity prevalence increasing from approximately 45% in those aged 40 years and above to over 74% in those above 80 years, and with meta-analytic evidence demonstrating significantly higher odds of multimorbidity in those aged 70 years and above compared with younger old-age groups (6,9). This pattern likely reflects the cumulative biological effect of prolonged exposure to risk factors, progressive decline in organ reserve, and the compounding nature of chronic disease, whereby the presence of one condition often predisposes to the development of others through shared pathophysiological pathways, as has been demonstrated through factor-analytic identification of non-random comorbidity clusters — such as cardiovascular, induced-dependency, and osteoarticular patterns — in hospitalised older populations (12,13). These findings carry important clinical implications. The high prevalence of multimorbidity, and particularly the substantial proportion of patients with four or more comorbid conditions, underscores the inadequacy of a single-disease-focused approach to the care of elderly patients and supports the routine incorporation of comprehensive geriatric assessment, which can systematically capture functional, cognitive, and psychosocial dimensions alongside the purely biomedical comorbidity profile (10,11). Limitations of the present study include its cross-sectional, single-centre design, which precludes assessment of the temporal sequence in which comorbidities developed, and its hospital-based sampling frame, which may not be representative of the broader community-dwelling elderly population and could overestimate true population-level multimorbidity prevalence due to referral bias. Longitudinal, community-based studies would further strengthen understanding of how comorbidity patterns evolve over time in this population.

This study demonstrates that multimorbidity is highly prevalent among elderly patients attending tertiary care, affecting nearly two-thirds of the study population, with hypertension and type 2 diabetes mellitus emerging as the dominant comorbid conditions, both individually and in combination. Multimorbidity burden rises sharply with advancing age and is significantly higher among women than men. These findings reinforce the need for a shift away from single-disease-oriented care toward integrated, person-centred geriatric care models that incorporate comprehensive geriatric assessment, recognise common comorbidity clusters, and proactively address the compounding healthcare needs of the rapidly growing elderly population.

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