Prevalence and factors associated with uncontrolled systolic blood pressure among treated older adults in Sri Lanka: a nationwide multicenter cross-sectional study

Abstract

Background

Uncontrolled systolic blood pressure (SBP) is a major modifiable determinant of cardiovascular morbidity and mortality in older adults. This study aimed to evaluate the prevalence, associated factors, and cardiovascular implications of uncontrolled SBP among treated older adults in Sri Lanka.

Methods

A nationwide multicenter cross-sectional study was conducted in medical outpatient clinics of ten tertiary care hospitals representing all nine provinces of Sri Lanka. A total of 1,339 adults aged ≥ 65 years receiving antihypertensive therapy for at least six months were recruited using systematic sampling. Blood pressure (BP) was measured using a standardized three-reading protocol. Uncontrolled SBP was defined as SBP ≥ 130 mmHg irrespective of diastolic BP, in accordance with contemporary guideline recommendations. Data was collected using interviewer-administered questionnaires and medical record review. Associations between patient characteristics and uncontrolled SBP were assessed using chi-square tests, independent samples t-tests, and multivariable logistic regression analysis.

Results

The mean age of participants was 69.4 ± 6.6 years, and 56.8% were female. The mean duration of hypertension was 9.8 ± 8.3 years. Uncontrolled SBP was present in 71.2% of treated older adults. Only 34.4% were receiving dual antihypertensive therapy, while 42.2% remained on monotherapy. Major adverse cardiovascular events (MACE) were reported in 38.2% of participants, and other vascular comorbidities were present in 81.6%. In multivariable analysis, satisfactory income (OR 1.96, 95% CI 1.20–3.20, p = 0.007), low physical activity (OR 1.41, 95% CI 1.07–1.86, p = 0.015), and higher neck circumference (OR 1.01, 95% CI 1.01–1.02, p = 0.014) were independently associated with uncontrolled SBP. Importantly, uncontrolled SBP was significantly associated with MACE (OR 1.31, 95% CI 1.01–1.69, p = 0.044). Medication adherence, dietary salt intake, BMI, and vascular comorbidities were not independently associated with uncontrolled SBP.

Conclusions

Over two-thirds of treated older adults in Sri Lanka had uncontrolled SBP, which was more common among participants with MACE. Higher income, low physical activity, and increased neck circumference were associated with uncontrolled SBP among treated older adults.

These findings highlight the importance of targeted strategies, including lifestyle modification and improved risk-based management, to optimize BP control in this population.

Background

More than half a billion people worldwide are affected by cardiovascular diseases (CVDs), the leading cause of death globally, accounting for 20.5 million deaths in 2021 [1, 2]. Arterial hypertension is a major yet largely preventable risk factor for cardiovascular disease–related morbidity and mortality [3]. Evidence from multiple studies indicates a consistent, linear relationship between achieved systolic blood pressure (SBP) and the risk of cardiovascular events and death [4]. With advancing age, blood pressure (BP) patterns undergo characteristic changes; SBP continues to rise linearly, while diastolic blood pressure (DBP) tends to plateau or decline after the fifth or sixth decade of life [5]. This physiological shift makes isolated systolic hypertension (ISH), defined as SBP ≥ 140 mmHg with DBP < 90 mmHg, the most common form of elevated BP in the elderly population [6]. In parallel, the prevalence of uncontrolled SBP, defined in accordance with recent guidelines as SBP ≥ 130 mmHg, increases markedly with advancing age, even among individuals receiving antihypertensive therapy [7–9]. Several major studies have consistently demonstrated that SBP is a strong and independent risk factor for cardiovascular disease and mortality in older adults [10].

With advancing age, repetitive cyclical mechanical stress leads to progressive fragmentation and degradation of elastin fibers, accompanied by increased collagen deposition [11]. These structural changes increase arterial stiffness and impair the buffering capacity of conduit vessels. This would result in aortic impedance to pulsatile blood flow, resulting in amplification of the forward pressure wave for a given stroke volume. Consequently, SBP rises disproportionately, while DBP tends to decline, leading to widening of pulse pressure (PP). Elevated pulse pressure (PP) not only reflects systemic atherosclerotic burden in arteries but also contributes to further plaque development and instability [12]. Besides, this hemodynamic alteration increases cardiac workload and contributes to adverse cardiovascular outcomes in old age [11, 13]. Increased arterial stiffness limits the ability of pharmacological agents to effectively lower SBP, as elevated pressure is driven predominantly by reduced vascular compliance rather than increased peripheral resistance [14].

Robust evidence demonstrates that intensive SBP control provides substantial cardiovascular benefits even in older adults. Large, randomized trials, including SPRINT and STEP, have shown that targeting lower SBP levels significantly reduces major adverse cardiovascular events (MACE) and mortality in older adults, including those aged 75 years and above [15–17]. Moreover, intensive SBP control to a target of 110–130 mmHg in older patients has been shown to reduce total cardiovascular events by 26%, stroke by 30%, coronary events by 23%, and all-cause mortality by 13%, without compromising safety when carefully monitored [10]. A large individual participant–level meta-analysis from the Blood Pressure Lowering Treatment Trialists’ Collaboration, a 10 mmHg increase in SBP was shown to be significantly and independently associated with an approximately 10% increase in the risk of all fatal and non-fatal cardiovascular complications, with the exception of coronary events [18]. Collectively, this evidence highlights that SBP is a stronger predictor of cardiovascular outcomes which shows the importance of treating BP as a continuous risk factor rather than a dichotomous condition. Therefore, optimal SBP control should be pursued as an integral component of comprehensive cardiovascular risk management, even in the old age [19]. Considering recent trial evidence, the 2024 European Society of Cardiology (ESC) hypertension guidelines represent a paradigm shift in BP management by endorsing lower SBP targets than previously recommended. The guidelines recognize the cardiovascular benefits of more intensive SBP lowering across adult populations, including older individuals, while emphasizing the importance of individualized treatment based on treatment tolerance, comorbidities, and frailty rather than chronological age alone [9].

Despite being easily diagnosable and relatively affordable to manage, uncontrolled SBP often remains underrecognized and undertreated in older population [20, 21]. Poor SBP control among older adults has been associated with several behavioral and sociodemographic factors. Low medication adherence has been identified as an important contributor to uncontrolled SBP, as inconsistent use of antihypertensive medications reduces the effectiveness of treatment [22]. In contrast, regular physical activity has been shown to play a protective role in BP regulation, with both aerobic and static exercises demonstrating significant reductions in BP among middle-aged and older adults [23]. Studies have also reported disparities in SBP control across different ethnic groups, with Non-Hispanic Black individuals showing a higher prevalence of uncontrolled hypertension. Additionally, higher body mass index (BMI), living alone, and low income have been associated with poorer SBP control, likely reflecting the influence of obesity and social determinants of health on SBP management in older populations [24].

In Sri Lanka, the demographic shift is particularly striking, with adults aged 65 and above comprising 11.9% of the total population in 2023, the highest proportion in South Asia [25, 26].

Although Sri Lanka is a low-middle-income country (LMIC), it has invested significantly in public health and maintains the highest per capita government health expenditure in South Asia [27]. By 2041, it is estimated that one in four Sri Lankans will be aged 65 years and above, placing considerable pressure on healthcare systems and the working-age population [26, 28]. This aging trend, coupled with the rise in non-communicable diseases (NCDs), underscores the urgent need for adaptive healthcare strategies tailored to older populations in Sri Lanka [29, 30]. Therefore, ensuring optimal hypertension management in the older adults is not only a clinical priority but also a cost-effective public health strategy for Sri Lanka.

However, robust global data on uncontrolled SBP among older adults are limited, with most evidence derived from high-income countries. Evidence from LMICs, especially South Asia remains particularly scarce. This lack of region-specific evidence represents a critical gap in understanding the true burden and determinants of poor SBP control in resource-limited settings.

In South Asia as well as in Sri Lanka, despite the known benefits of treatment and introduction of guidelines, hypertension remains undertreated, contributing to avoidable morbidity and mortality [31, 32]. Nationally representative data on uncontrolled SBP using contemporary treatment targets is currently lacking. Given the significant cardiovascular risks associated with uncontrolled SBP, the rapidly ageing population in Sri Lanka, and the limited availability of local data, this study aimed to estimate the prevalence of uncontrolled SBP and examine its demographic, clinical, and behavioral associations and related outcomes among older adults with hypertension. By elucidating the magnitude and associations of inadequate SBP control, this study aims to inform targeted clinical interventions and public health strategies, ultimately contributing to improved cardiovascular outcomes and healthier ageing in this vulnerable population.

Methodology

Study design and study setting

This was a multicenter, cross-sectional study conducted in medical outpatient clinics of ten tertiary care facilities across all nine provinces of Sri Lanka. The study was conducted in out-patient medical clinics that provide long-term follow-up care to individuals with hypertension and other medical conditions. The study was conducted between 1st March 2025 and 31st August 2025 among older adults aged 65 years or above who have been diagnosed with hypertension for at least six months on treatment, following the STROBE statement. The study aims were to determine the prevalence, associations and cardiovascular implications of uncontrolled SBP among older adults.

The study was conducted in ten tertiary care hospitals across all nine provinces in Sri Lanka; National Hospital Galle in the Southern province; Colombo South Teaching Hospital; University Hospital of Kotelawala Defense University in the Western province; Teaching Hospital Peradeniya in the Central province; Teaching Hospital Jaffna in the Northern province, Rathnapura Teaching Hospital in the Sabaragamuwa province, Teaching Hospital Anuradhapura from North central province, Teaching Hospital Batticaloa from Eastern province, Teaching Hospital Kurunegala from Wayamba province, and Teaching Hospital Badulla from Uva province The ethical clearance for the study was granted by the Ethics Review Committee, Teaching Hospital Karapitiya, Sri Lanka (THK/ERC/24/2). Before the commencement of the study, all the study subjects signed a written informed consent.

Study population and study sample

The study population consisted of older adults aged 65 years and older with a confirmed diagnosis of hypertension who had been receiving antihypertensive therapy for at least six months and were attending routine medical outpatient clinics at the selected tertiary care centers during the study period. Patients were excluded if they had an acute medical condition that required immediate hospitalization at the time of recruitment, secondary hypertension, moderate to severe cognitive impairment and/or dementia, or a psychiatric disorder that prevented reliable participation, a terminal illness, or a significant physical condition that interfered with accurate BP measurement.

Sample size determination and sampling procedure

The sample size was calculated using the single population proportion formula with a 95% confidence level (α = 0.05) and a margin of error of 2.5%, as described by Lwanga and Lemeshow (1991) [33]. In the absence of published Sri Lankan data on SBP control among older adults, the expected proportion of uncontrolled SBP was assumed to be 50% to obtain the maximum sample size. The minimum required sample size was therefore calculated as 388 participants, which was increased to 427 after allowing for a 10% non-response rate.

A multistage sampling technique was used. In the first stage, ten tertiary care hospitals were selected to ensure geographical representation across Sri Lanka. In the second stage, participants were recruited from the medical outpatient clinics of the selected hospitals. Although the minimum required sample size was 427, a larger sample was intentionally recruited to improve the precision of prevalence estimates, enhance representativeness across study centers, and strengthen the external validity of the findings. Each clinic had an estimated 1,200 registered older adults with hypertension attending routine follow-up care. To ensure adequate representation from each center, approximately 120 participants were targeted per clinic. Consequently, a total of 1,339 participants were recruited from the ten hospitals during the study period. Within each clinic, systematic random sampling was employed. The sampling interval was calculated as ten by dividing the estimated clinic population by the target sample size per clinic (1,200/120). A random starting point was selected from the clinic register, after which every tenth eligible patient was invited to participate. On each clinic day, approximately ten eligible participants were enrolled, irrespective of gender, until the allocated sample size for each center was achieved.

Data collection methods and tools.

Sociodemographic and disease-related data were collected using a semi-structured interviewer-administered questionnaire in Sinhala or English, according to participants’ preference. Relevant clinical information was additionally extracted from available clinical records. Written informed consent was obtained from all participants, and participant confidentiality and anonymity were maintained throughout the study to minimize potential bias in self-reported data.

A one-day training programme was conducted for pre-intern medical officers who served as interviewers across the ten participating tertiary care hospitals to standardize data collection procedures, including questionnaire administration and blood pressure measurements. Participants retained the right to withdraw from the study at any point without penalty or negative consequences.

Age, sex, ethnicity, education level, marital status, employment status, current living arrangements, and income were assessed as the sociodemographic characteristics, where multiple options were given by the interviewer to select for each characteristic. Monthly household income was categorized using 50,000 LKR as a pragmatic cut-off to broadly differentiate lower- and higher-income groups within the study population. This threshold was used for analytical stratification and practical interpretability, rather than as a formal socioeconomic classification or direct representation of the national poverty line. Disease-related information was collected from both the patient and their clinical records.

Operationalization of variables

Systolic and diastolic BP were measured using an OMRON HEM-7320 automatic BP monitor (Omron Corp., Kyoto, Japan). Three consecutive readings were obtained 10 min apart after participants had rested for 10 min in a seated position, with the arm supported at heart level.

Measurements were taken from the right arm unless contraindicated. All devices were validated for accuracy against a mercury column sphygmomanometer. The ESC 2024 guideline recommends a target SBP of 120–129 mmHg in treated patients, when tolerated, with individualization according to age, frailty, comorbidities, and treatment tolerance. Accordingly, uncontrolled SBP was defined as SBP ≥ 130 mmHg irrespective of DBP, based on ESC 2024 guideline recommendations and evidence from major clinical trials supporting intensive SBP control in eligible older adults [9, 16, 17]. These definitions were used to reflect contemporary ESC treatment targets while maintaining comparability with global epidemiological studies.

Physical activity level (PAL) was assessed based on the validated Sinhala version of the International Physical Activity Questionnaire (IPAQ) [34]. In addition, height was assessed to the nearest 0.1 cm utilizing a Seca 240 cm height measurement device (Seca GmbH, Hamburg, Germany). Weight was recorded to the nearest 0.1 kg with the aid of an OMRON BF511 Body Composition Monitor. The body mass index (BMI) was calculated by dividing weight (kg) by height (m) squared. In addition, Neck circumference was measured in centimeters (cm) at the level of the laryngeal prominence, while waist circumference (cm) was measured just above the umbilicus.

Medication adherence for antihypertensive therapy was assessed using the validated Sinhala version of the brief medication questionnaire [35]. Dietary salt intake was assessed using a visual analogue scale ranging from 1 to 10, where scores of 1–3 indicated low intake, 4–7 moderate intake, and 8–10 high salt intake. Major adverse cardiovascular events (MACE) were operationally defined as a composite of documented stroke, transient ischemic attack, coronary artery disease, and heart failure, based on participant history and medical record review, adapted from standardized cardiovascular and stroke endpoint definitions [22]. Diabetes mellitus, dyslipidemia, and chronic kidney disease were considered vascular comorbidities.

Data analysis

Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) (version 25.0). The normality of continuous variables was assessed using the Anderson–Darling test. Missing data accounted for approximately 5% of the dataset. For continuous variables, missing values were handled using mean imputation after assessment of normality. For categorical variables, missing values were handled using mode imputation. Continuous variables are presented as means with standard deviations (SD), while categorical variables are summarized as frequencies and percentages. Independent-samples t-tests were used to compare mean serum creatinine levels according to hypertension status, including the presence versus absence of uncontrolled SBP. Physical activity was assessed using the International Physical Activity Questionnaire (IPAQ), and participants achieving ≥ 3000 metabolic equivalent task (MET) minutes per week were classified as physically active.

Associations between independent variables and uncontrolled SBP were assessed using the Chi-square test. Socio-demographic factors (sex, age, educational level, occupational status, income, living status, and marital status), disease-related factors (age at diagnosis of hypertension, duration of hypertension, and BP control status), treatment-related factors (type of antihypertensive medication and medication adherence), and other potential factors (family history of hypertension and physical activity level) were considered as independent variables. Variables with a p-value less than 0.25 in bivariate analysis were included in a multivariable logistic regression model using the enter method to adjust for potential confounders. Multicollinearity among variables included in the multivariable logistic regression model was assessed using Variance Inflation Factors (VIF), and no significant multicollinearity was observed. Results are reported as odds ratios (ORs) with 95% confidence intervals (CIs). A two-sided p-value < 0.05 was considered statistically significant.

Results

Demographic characteristics

A total of 1,339 older adults were included in the final analysis. The mean age of participants was 69.4 ± 6.6 years, and 56.8% were female. The mean age at diagnosis of hypertension was 59.6 ± 9.7 years, with an average disease duration of 9.8 ± 8.3 years at the time of the study. A family history of hypertension among first-degree relatives was reported by 54.3%(n = 724) of participants. Most participants were married and living with their spouses 78.4% (n = 1,050), while 3.2% (n = 43) were unmarried, 0.5% (n = 7) were separated or divorced, and 17.9% (n = 239) were widowed. Most older adults resided in extended family households 78.4% (n = 1,050), whereas 21.6% (n = 289) lived in nuclear family arrangements. MACEs were reported in 38.2% (n = 511) of participants, while vascular comorbidities were highly prevalent, affecting 81.6% (n = 1,093) of the study population. Additional baseline characteristics, including detailed sociodemographic information, are presented in Table 1.

Table 1.

Baseline characteristics of the study sample (n = 1339)

Variable	Results (Number and percentage)
Female gender	760 (56.8)
Ethnicity
Sinhala	1050 (78.4)
Others (Tamil, Muslim, Burger)	289 (21.6)
Age group
65–74years (young old)	1045 (78.05)
75 years and above (old old)	294 (22.0)
Mean ± SD age (years)	69.4 ± 6.6
Age at the diagnosis of Hypertension
Before 40 years	29(2.2)
40 years and above	1310 (97.8)
Mean ± SD age at the diagnosis of hypertension (years)	59.6 ± 9.7
Duration of the Hypertension
Less than 10 years	752(56.2)
10 years and above	587 (43.8)
Mean ± SD duration of the Hypertension	9.8 ± 8.3
Employment status
Employed in a regular job/retired	615 (45.9)
Unemployed	724(54.1)
Educational level
Secondary education-not completed	1102 (82.3)
Secondary education-Completed	237 (17.7)
Monthly income (LKR)
Satisfactory (50,000 and above)	131 (9.8)
Unsatisfactory (below 50,000)	1208 (90.2)
Presence of other vascular comorbidities
Diabetes Mellitus	788 (58.8)
Dyslipidemia	786 (58.9)
Chronic kidney disease	114 (8.5)
Presence of MACE
Coronary artery diseases	403(30.1)
Stroke	117(8.7)
Transient ischemic attack	41(3.1)

Cardiovascular risk profile and lifestyle characteristics of the study population

Uncontrolled SBP was present in 71.2% (n = 953) of the study population. As shown in Table 2, only 34.4% of patients were receiving standard dual antihypertensive therapy. Angiotensin receptor blockers (ARBs) and calcium channel blockers (CCBs) were the most prescribed antihypertensive medications, used by 69.3% and 38.8% of participants, respectively. Medication adherence was high in this cohort, with 62.1% demonstrating high adherence to antihypertensive therapy.

Table 2.

BP status, antihypertensive treatment patterns, and related clinical characteristics of the study population (n = 1339)

Variable	Results (Number and percentage)
BP Control status
Uncontrolled SBP	953(71.2)
Mean ± SD SBP (mmHg)	139.1 ± 21.8
Mean ± SD DBP (mmHg)	79.3 ± 12.1
Antihypertensive therapy
Monotherapy	565 (42.2)
Dual therapy	460 (34.4)
Poly therapy	314 (23.5)
Type of antihypertensive medication*
ACEI	210(15.6)
ARB	928(69.3)
Thiazide diuretics	212(15.8)
Mineralocorticoid receptor blockers	62(4.6)
Centrally acting drug	36(2.7)
Alpha blockers	149(11.1)
Beta blockers	224(16.7)
Loop Diuretics	142(10.6)
CCB	519(38.8)
Adherence to drugs
Low	96(7.2)
Moderate	411(30.7)
High	832(62.1)
Salt intake
Minimum	358(26.7)
Moderate	894(66.8)
High	87(6.5)
Physical activity level
Low	417 (31.1%)
Moderate/high	922 (68.9%)
Alcohol use	31 (2.3%)
Smoking history	43 (3.2%)

*Multiple responses

Most participants were receiving lipid-lowering therapy 81.4% (n = 1,090), and more than half were prescribed antiplatelet agents 54.6% (n = 731), with 51.9% (n = 695) receiving both therapies.

Lifestyle risk factors were relatively uncommon: 3.2% (n = 43) reported smoking and 2.3% (n = 31) reported alcohol consumption. Based on the IPAQ, nearly one-third of participants (n = 417; 31.1%) had low physical activity levels, while 53.8% (n = 721) and 15.0% (n = 201) demonstrated moderate and high activity levels, respectively. Most participants reported moderate dietary salt intake (66.8%).

Associated factors for uncontrolled SBP

No significant differences were observed in body mass index (BMI) or waist circumference between participants with and without uncontrolled systolic blood pressure (SBP). However, neck circumference was significantly higher among participants with uncontrolled SBP (Table 3). In addition, serum creatinine levels did not differ significantly between participants with and without uncontrolled SBP (1.2 ± 1.4 mg/dL vs. 1.1 ± 0.9 mg/dL; t = 1.68, p = 0.092).

Table 3.

Anthropometric parameters according to uncontrolled SBP status (n = 1339)

Variable	Uncontrolled SBP
	Yes (n = 953) Mean (SD)	No (n = 386) Mean (SD)	T statistics (P value)
BMI (kg/m2)	24.9(8.6)	24.1(4.4)	1.76 (0.078)
Neck circumference(cm)	39.7(18.6)	36.4(12.1)	3.71 (< 0.001) *
Waist circumference(cm)	86.6(17.0)	85.8(14.4)	-0.161 (0.872)

*Statistically significant at 0.05 significance level

Participants with satisfactory income (≥ LKR 50,000) had a higher proportion of uncontrolled systolic blood pressure (SBP) compared with those with unsatisfactory income (81.7% vs. 68.5%; χ² = 9.70, p = 0.002). Physical activity level also differed significantly according to SBP control status, with a higher proportion of participants with low physical activity having uncontrolled SBP compared with those with moderate or high physical activity levels (76.0% vs. 69.0%; χ² = 6.93, p = 0.008). In contrast, gender, age, employment status, alcohol consumption, smoking, dietary salt intake, presence of vascular comorbidities, use of dual antihypertensive therapy, adherence to antihypertensive medications, and duration of hypertension did not differ significantly according to SBP control status (all p > 0.05). The presence of MACE also differed significantly according to SBP control status, with a higher proportion of participants with MACE having uncontrolled SBP compared with those without MACE (74.8% vs. 69.0%; χ² = 5.17, p = 0.023) (Table 4).

Table 4.

Factors associated with uncontrolled SBP (n = 1339)

Variable	Uncontrolled SBP Yes (N = 953) n (%)	Uncontrolled SBP No (N = 386) n (%)	χ² (df = 1)	p value
Gender
Male	423 (73.1)	156 (26.9)	1.77	0.184
Female	530 (69.7)	230 (30.3)
Age
< 75 years	743 (71.1)	302 (28.9)	0.01	0.913
≥ 75 years	210 (71.4)	84 (28.6)
Employment status
Employed/retired	430 (69.9)	185 (30.1)	0.87	0.351
Unemployed	523 (72.2)	201 (27.8)
Monthly Income LKR
Satisfactory (≥ 50,000)	107 (81.7)	24 (18.3)	9.70	0.002*
Unsatisfactory (< 50,000)	785 (68.5)	361 (31.5)
Alcohol use
Yes	24 (77.4)	7 (22.6)	0.62	0.433
No	926 (71.0)	379 (29.0)
Smoking
Yes	34 (79.1)	9 (20.9)	1.36	0.243
No	915 (70.9)	376 (29.1)
Body mass index
Undernutrition/normal	385 (70.1)	164 (29.9)	0.50	0.482
Overweight/obesity	568 (71.9)	222 (28.1)
Physical activity level
Low	317 (76.0)	100 (24.0)	6.93	0.008*
Moderate/high	636 (69.0)	286 (31.0)
Salt intake
Low/moderate	887 (70.8)	365 (29.2)	1.00	0.318
High	66 (75.9)	21 (24.1)
Presence of other vascular comorbidities
Yes	773 (70.7)	320 (29.3)	0.59	0.444
No	180 (73.2)	66 (26.8)
Presence of MACE
Yes	382(74.8)	129(25.2)	5.17	0.023*
No	571(69.0)	257(31.0)
Dual antihypertensive therapy
Yes	332 (72.2)	128 (27.8)	0.34	0.558
No	621 (70.6)	258 (29.4)
Adherence to antihypertensives
Low/moderate	376 (74.2)	131 (25.8)	3.55	0.059
High	577 (69.4)	255 (30.6)
Duration of hypertension
< 10 years	537 (71.4)	215 (28.6)	0.05	0.828
≥ 10 years	416 (70.9)	171 (29.1)

*Statistically significant at 0.05 significance level

In the multivariable analysis (Table 5), several factors were independently associated with uncontrolled SBP. Participants with satisfactory income (OR 1.96, 95% CI 1.20–3.20, p = 0.007), low physical activity (OR 1.41, 95% CI 1.07–1.86, p = 0.015), higher neck circumference (OR 1.01, 95% CI 1.01–1.02, p = 0.014), and the presence of MACE (OR 1.31, 95% CI 1.01–1.69, p = 0.044) were significantly associated with uncontrolled SBP after adjustment for potential confounders. In contrast, gender, adherence to antihypertensive medications, and smoking status were not significantly associated with uncontrolled SBP.

Table 5.

Multivariable logistic regression analysis of factors associated with uncontrolled SBP (n = 1339)

Variable	B	S.E.	Wald	df	Sig.	OR	95% CI for OR
							Lower	Upper
Presence of MACE	0.266	0.132	4.072	1	0.044*	1.305	1.008	1.691
Low/moderate adherence to antihypertensives	0.181	0.135	1.808	1	0.179	1.198	0.921	1.560
Low physical activity level	0.342	0.141	5.902	1	0.015*	1.408	1.068	1.855
Smoking	0.388	0.397	0.956	1	0.328	1.474	0.677	3.210
Having a satisfactory income	0.673	0.250	7.273	1	0.007*	1.961	1.202	3.199
Male gender	0.037	0.133	0.077	1	0.782	1.038	0.799	1.347
Neck Circumference	0.012	0.005	6.021	1	0.014*	1.013	1.003	1.023
BMI	0.016	0.014	1.412	1	0.235	1.017	0.989	1.045
Constant	-0.404	0.369	1.203	1	0.273	0.667

*Statistically significant at 0.05 significance level

Discussion

This multicenter cross-sectional study was conducted in the outpatient clinics of ten tertiary care hospitals across all nine provinces of Sri Lanka, involving 1,339 older adults with hypertension, to provide a comprehensive assessment of uncontrolled SBP, including its associated factors, and effects on the local geriatric population. In this cohort, the mean age of participants was 69.4 years (SD 6.6), the mean SBP was 139.1 (SD 21.8), and 56.8% were female. A substantial proportion of patients (71.2%) had uncontrolled SBP, while only one-third (34.4%) were receiving standard dual antihypertensive therapy, highlighting potential gaps in treatment optimization. According to the analysis, uncontrolled SBP was significantly associated with satisfactory income (p = 0.007), low physical activity (p = 0.015), and higher neck circumference (p = 0.014). However, study outcomes indicate that poor medication adherence, salt intake, BMI, smoking, alcohol use, and vascular comorbidities have not significantly accounted for uncontrolled SBP in older Sri Lankan adults.

Importantly, uncontrolled SBP was independently associated with the presence of MACE (p = 0.044). This study highlights major deficiencies in hypertension management and their future impact on cardiovascular morbidity among treated older adults in Sri Lanka. By identifying key associated factors, it provides important insight for developing targeted interventions aimed at reducing adverse cardiovascular events in this population.

The prevalence and determinants of hypertension among Sri Lankan adults have been examined by the Sri Lanka Health and Ageing Study (SLAAS) 2018–2019, a nationally representative analysis. The SLAAS investigation revealed that nearly one-third of the adult population has hypertension, and further, its prevalence escalated with increasing age, peaking between 70 and 79 years [36]. However, SLAAS did not adequately document the prevalence of uncontrolled SBP among hypertensive older individuals, thereby highlighting the urgent requirement for more extensive data regarding SBP control among this demographic within the Sri Lankan geriatric population. Hypertension within the Sri Lankan geriatric population. As a novel analysis, our study identified that nearly three-fourths of geriatric individuals with hypertension in Sri Lanka exhibited uncontrolled SBP, for which SBP was operationally defined as ≥ 130 mmHg in accordance with the BP standards recommended by the American Heart Association (AHA) 2017 and ESC 2024 guidelines. However, there is a notable lack of geriatric studies specifically focusing on uncontrolled SBP. Among the few available studies, SBP is commonly defined as ≥ 140 mmHg, whereas our study applied the more recent guideline threshold of ≥ 130 mmHg. As a result, the prevalence of uncontrolled SBP observed in our cohort cannot be directly compared with findings from other geriatric populations. A meta-analysis which included 200 studies and 2.6 million hypertensive patients, demonstrated that uncontrolled SBP (SBP ≥ 140 mmHg) was more common among older adults and varied considerably by region, with the highest prevalence reported in the Eastern Mediterranean (60.0%), followed by Africa (59.4%) and the Western Pacific (58.8%), while the lowest prevalence was observed in South-East Asia (44.2%) [37]. The use of SBP ≥ 130 mmHg as the definition of uncontrolled SBP was based on ESC 2024 guideline recommendations and evidence from major clinical trials, including SPRINT and STEP, which demonstrated cardiovascular benefits of intensive SBP lowering in eligible older adults. However, this threshold should not be interpreted as a universal treatment target for all older adults. In frail individuals, patients aged ≥ 80 years, or settings where routine frailty assessment and intensive monitoring are limited, a less intensive SBP target, such as < 140 mmHg may be more pragmatic and safer.

Therefore, BP targets in older adults should be individualized according to frailty, comorbidities, functional status, and treatment tolerance. In this context, our study highlights uncontrolled SBP as an important public health concern among older adults and emphasizes the need for targeted interventions to improve SBP control in this vulnerable population, both locally and globally.

In the present study, 42.2% of geriatric hypertensive patients received monotherapy, while 34.4% were on standard dual therapy. The most prescribed antihypertensive agents were angiotensin receptor blockers (ARBs), calcium channel blockers (CCBs), and beta blockers, consistent with previous reports on prescribing patterns [38–40]. Similar trends have been observed internationally, with 38.8% of older adults in Spain [41] and 51.3% in Malaysia [42] receiving monotherapy. In contrast, a large study from southern China reported that 68.6% of geriatric hypertensive patients were on combination therapy [43], suggesting considerable variation in treatment practices across regions. Therapeutic inertia in older adults may arise from concerns regarding polypharmacy, postural hypotension, and other treatment-related adverse effects. In addition, limited adherence to age-appropriate hypertension guidelines may lead physicians to favor monotherapy in geriatric patients [39, 44, 45]. These findings highlight the need to optimize antihypertensive therapy in older adults, particularly through the appropriate use of combination therapy, to improve BP control and reduce cardiovascular risk. Recent landmark trials, including the Systolic Blood Pressure Intervention Trial (SPRINT) and the Strategy of Blood Pressure Intervention in Elderly Hypertensive Patients (STEP) trials, together with the ESC 2024 guidelines [9], recommend dual antihypertensive therapy in older adults, similar to younger populations, to achieve intensive BP control and reduce mortality and cardiovascular events. Hence, the relatively high reliance on monotherapy in this cohort, together with the high prevalence of uncontrolled SBP, may suggest possible undertreatment in this population. This may partly reflect physician-related factors such as therapeutic inertia, concerns regarding polypharmacy and treatment-related adverse effects in older adults, or variations in adherence to contemporary hypertension management guidelines. These findings highlight the need to further explore provider-level and health-system factors influencing treatment intensification among older adults with uncontrolled SBP. Considering current guideline recommendations that prefer early dual antihypertensive therapy for optimal SBP control, it is reasonable to hypothesize that greater use of combination therapy could potentially improve SBP control in this setting. These results highlight the urgent need to increase awareness within healthcare systems about the benefits of dual therapy and to address therapeutic inertia. Implementing individualized treatment strategies for geriatric patients can optimize antihypertensive regimens while balancing safety concerns, ultimately improving both BP control and cardiovascular outcomes.

According to the analysis, uncontrolled SBP was significantly associated with satisfactory income (p = 0.007), while many studies have found that lower or moderate-income status is positively associated with uncontrolled SBP [24, 46, 47]. However [48], found a positive association between relative wealth and higher SBP in adjusted multilevel models across the general adult population.

Moreover, our study found that low physical activity (p = 0.015) was significantly associated with uncontrolled SBP. Supporting our study observations, a study by [30] reports that low physical activity, combined with persistently elevated SBP (> 130 mmHg) during mid-to-late life, was associated with higher SBP in older adults. Similarly, a Bangladeshi cross-sectional study and a systematic review concluded that older adults engaged in higher levels of physical activity had lower SBP, while those with low physical activity levels had higher SBP [49, 50]. Speculatively, older adults with a satisfactory income may be less likely to engage in regular physical activity and more likely to lead sedentary lifestyles or work in less physically demanding occupations, which could contribute to uncontrolled SBP. Furthermore, our study identified a significant association between uncontrolled SBP and increased neck circumference (p = 0.014). This outcome is consistent with previous research showing a positive correlation between neck circumference and SBP, suggesting that individuals with larger neck circumference tend to have higher SBP [51–53] These observed associations may be explained by lifestyle patterns among individuals where reduced physical activity and calorie-dense dietary habits contribute to weight gain and central adiposity [51, 54, 55]. Increased neck circumference reflects upper-body fat accumulation, which is strongly linked to obstructive sleep apnea and sympathetic overactivity, both of which contribute to persistent elevation of SBP [53, 54, 56]. Therefore, the combined effects of income status, physical inactivity, and upper-body fat accumulation may explain the higher likelihood of uncontrolled SBP in this group.

A key finding of this study was the lack of a significant association between uncontrolled SBP and traditional modifiable risk factors such as medication adherence, salt intake, BMI, smoking, alcohol use, and NCD comorbidities. However, these factors are well-established determinants of hypertension in adults and younger hypertensive populations [57–62]. The absence of significant associations for these factors in our study population may be explained by age-related arterial stiffness, long-standing vascular remodeling, multimorbidity, and complex treatment patterns, which likely play a more dominant role in BP regulation and diminish the observable impact of individual lifestyle factors [39, 56, 63] However, several studies in the existing literature findings are consistent with ours, demonstrating that medication adherence [64], dietary salt intake, and alcohol consumption [39, 65] are not significantly associated with uncontrolled SBP among geriatrics across different global settings. Although major vascular comorbidities, including diabetes mellitus, dyslipidemia, and CKD, were assessed in this study, they were not independently associated with uncontrolled SBP. This may be partly explained by the uniformly high burden of comorbidities in the study population, which may have reduced observable differences between groups. In addition, treatment intensification and closer clinical follow-up among patients with multiple comorbidities may have attenuated the expected associations with poor BP control. The absence of these associations in the present cohort may also be explained by several methodological limitations, including reliance on self-reported measures of lifestyle behaviors such as dietary salt intake, smoking status, alcohol consumption, and medication adherence, which may have introduced misclassification and recall bias [66, 67]. These limitations are mostly relevant in a geriatric population, where cognitive impairment and reporting inaccuracies are more common [56].

Importantly, our study found that uncontrolled SBP was significantly associated with MACE in this cohort. This is supported by evidence from large studies, including the Framingham Heart Study [68], SPRINT and STEP, which identified SBP as a strong independent predictor of cardiovascular events in aging populations. Moreover, persistently elevated SBP has been shown to increase arterial stiffness and cardiac workload, contributing to the development of stroke, coronary artery disease, and heart failure [69, 70]. A large longitudinal population-based Korean study and a systematic analysis of 24 studies [70, 71], demonstrated that uncontrolled SBP was significantly associated with an increased risk of cardiovascular events in the geriatric population. Furthermore, another recent systematic review states that the reduction of SBP in patients aged ≥ 75 years was significantly associated with the minimization of cardiovascular events, and intensive SBP lowering to below 130 mmHg reduces composite cardiovascular events (RR: 0.61, 95% CI: 0.40–0.94) in older hypertensive adults without increasing serious adverse events [72] suggesting that utilization of standard dual antihypertensive therapy may not only enhance SBP control but also play a crucial role in reducing major cardiovascular events in this population.

Together, these findings highlight the critical importance of achieving optimal SBP control in older adults to reduce the risk of major cardiovascular events, emphasizing the need for targeted strategies in geriatric hypertension management.

The unique contribution of this study is that it provides multicenter evidence from Sri Lanka, a rapidly ageing South Asian LMIC, demonstrating a high burden of uncontrolled SBP among treated older adults and identifying locally relevant demographic, clinical, and behavioral factors that may guide targeted interventions and health-system planning. This study was conducted among a large sample of older adults across ten tertiary care hospitals representing all nine provinces of Sri Lanka, enhancing the applicability of the findings to real-world outpatient settings.

To our knowledge, this is the first study to comprehensively examine the prevalence and associated factors of uncontrolled SBP among treated older hypertensive adults in the country using contemporary SBP thresholds. The use of standardized BP measurement protocols, systematic data collection by trained interviewers, and validated instruments, including the locally validated medication adherence scale and IPAQ, strengthened the accuracy, consistency, and reliability of the data.

The study design was cross-sectional, which limits the ability to infer causality, and single-visit clinic BP measurements may not fully capture long-term BP control or variability. Data on lifestyle behaviors and medication adherence were largely self-reported, introducing potential recall and misclassification bias, although caregiver input and medical records were used where possible to improve accuracy. Recruitment from tertiary care hospitals may also limit the representativeness of the sample.

Building on these results, future research should focus on longitudinal studies to track BP trends over time and assess the impact of repeated BP measurements on SBP control. Further investigations into additional factors, such as obstructive sleep apnea and age-related vascular changes, could help clarify modifiable determinants of uncontrolled SBP in older adults. Studies targeting high-risk subgroups identified in this cohort, individuals with low physical activity, higher neck circumference, and those with satisfactory income, could guide personalized interventions and optimize antihypertensive therapy, ultimately aiming to reduce cardiovascular morbidity and mortality in this population. Additional sensitivity and subgroup analyses may provide further insight into regional and clinical variations in SBP control among older adults.

However, such analyses were beyond the primary scope of the present study and may be explored in future research. Furthermore, future studies using alternative SBP thresholds may further clarify the clinical applicability and robustness of these findings in older populations.

Conclusions

In conclusion, uncontrolled SBP is highly prevalent among treated older adults in Sri Lanka and is significantly associated with MACE, low physical activity, increased neck circumference, and socioeconomic factors, rather than traditional lifestyle or adherence-related variables. These findings underscore the urgent need for targeted strategies to optimize antihypertensive therapy, improve risk stratification, and address modifiable determinants, including physical inactivity and potential sleep-disordered breathing, to enhance cardiovascular outcomes in this high-risk geriatric population.

Abbreviations

AHA

American Heart Association

BMI

Body Mass Index

BP

Blood Pressure

CCBs

Calcium Channel Blockers

CI

Confidence Interval

CVDs

Cardiovascular diseases

DBP

Diastolic Blood Pressure

ESC

European Society of Cardiology

IPAQ

International Physical Activity Questionnaire

ISH

Isolated Systolic Hypertension

LMIC

Low-Middle-Income Country

MACE

Major Adverse Cardiovascular Events

MET

Metabolic Equivalent Task

NCDs

Non-Communicable Diseases

OR

Odds Ratio

PAL

Physical Activity Level

PP

Pulse Pressure

SBP

Systolic Blood Pressure

SD

Standard Deviation

SLAAS

Sri Lanka Health and Ageing Study

SPSS

Statistical Package for the Social Sciences

STROBE

Strengthening the Reporting of Observational Studies in Epidemiology

Authors' contributions

WDZ: Conceptualization, Data collection, Writing and reviewing, TPW: Conceptualization, Writing and reviewing, UKE: Writing and reviewing, ILAND: Formal analysis and methodology, RRMPC: Review & Editing. MMPTJ, SV, ATM, BR, PM, NP, LPMMKP: Data collection, Review & Editing.

Funding

Not applicable.

Data availability

The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

The study was conducted in accordance with the principles of the Declaration of Helsinki. Ethical approval was obtained from the Ethics Review Committee of Teaching Hospital Karapitiya, Sri Lanka (Ref: THK/ERC/24/02). Written informed consent was obtained from all participants prior to enrolment. The ethical approval for the research was obtained by the Ethics Review Committee at Teaching Hospital Karapitiya, Sri Lanka (THK/ERC/24/2). Before starting the research, all participants provided their written informed consent.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Clinical trial number

Not applicable.