European Journal of Cardiovascular Medicine

Chronic kidney disease (CKD) is a major global public health problem, characterized by progressive and irreversible decline in renal function and associated with a markedly increased risk of cardiovascular morbidity and mortality. Hypertension is both a leading cause and a frequent consequence of CKD, and its prevalence increases as kidney function deteriorates. Effective blood pressure (BP) control remains one of the most important modifiable factors in slowing CKD progression and reducing cardiovascular events; however, accurate assessment of BP in CKD patients continues to be a clinical challenge [1].

Globally, CKD affects approximately 10–13% of the adult population, with hypertension present in more than 80% of patients in advanced stages of disease [2]. In India, the burden of CKD is steadily rising due to increasing prevalence of diabetes mellitus, hypertension, aging population, and improved survival of patients with chronic diseases. Indian studies report hypertension prevalence ranging from 60% to over 90% among CKD patients, particularly in stages 4 and 5, highlighting the magnitude of the problem in routine clinical practice [3,4].

Conventionally, blood pressure assessment relies on office blood pressure monitoring (OBPM); however, OBPM has several inherent limitations. It provides only a snapshot measurement, is influenced by observer bias and patient anxiety, and fails to capture circadian BP variations. These limitations are particularly relevant in CKD patients, who commonly exhibit abnormal BP patterns such as masked hypertension, white-coat hypertension, nocturnal hypertension, and loss of normal nocturnal dipping [5]. Misclassification of BP status using OBPM alone may lead to under-treatment or over-treatment, thereby adversely affecting renal and cardiovascular outcomes.

Ambulatory blood pressure monitoring (ABPM) is increasingly recognized as the gold standard for BP assessment, as it provides multiple BP readings over a 24-hour period during routine daily activities and sleep. ABPM allows assessment of daytime and nighttime BP, BP variability, nocturnal dipping status, BP load, hyperbaric index, and percent time elevation—parameters that are not captured by office measurements [6]. Several studies have demonstrated that ABPM correlates better with target organ damage, including left ventricular hypertrophy, retinopathy, and progression of renal dysfunction, compared to OBPM [7].

Patients with CKD frequently exhibit altered circadian BP rhythm, most commonly a non-dipping or reverse-dipping pattern, which has been independently associated with faster decline in glomerular filtration rate and increased cardiovascular risk [8]. Nocturnal hypertension and elevated nighttime BP load are particularly common in advanced CKD and are strongly associated with resistant hypertension and target organ damage. ABPM plays a crucial role in identifying these high-risk phenotypes, which often remain undetected with routine clinic BP measurements [9].

Resistant hypertension—defined as uncontrolled BP despite the use of three or more antihypertensive agents including a diuretic—is highly prevalent in CKD patients and contributes significantly to cardiovascular morbidity. Studies using ABPM have shown that a substantial proportion of apparent resistant hypertension diagnosed by OBPM is due to white-coat effect, while true resistant hypertension is more accurately identified through ambulatory monitoring [10]. Similarly, masked hypertension, which carries a cardiovascular risk comparable to sustained hypertension, is frequently encountered in CKD patients and can only be reliably detected by ABPM [11].

Despite strong evidence supporting the clinical utility of ABPM, its use in hospitalized CKD patients remains limited in many centers, particularly in resource-constrained settings. There is a relative paucity of Indian data evaluating detailed ABPM parameters—such as hyperbaric index, percent time elevation, and nocturnal dipping patterns—across different stages of CKD. Understanding these patterns in hospitalized patients is especially important, as this group represents advanced disease with higher cardiovascular risk and frequent need for treatment optimization [12].

The present study aims to evaluate the clinical utility of 24-hour ambulatory blood pressure monitoring in hospitalized patients with chronic kidney disease by analyzing various ambulatory blood pressure parameters across different stages of CKD. It seeks to compare office blood pressure measurements with ambulatory blood pressure values to identify discrepancies in BP classification, and to determine the prevalence of resistant hypertension, masked hypertension, and white-coat hypertension in this population. The study also focuses on assessing altered circadian blood pressure patterns, including nocturnal non-dipping status, nighttime blood pressure load, hyperbaric index, and percent time elevation, and their association with disease severity and target organ damage. The findings of this study are expected to highlight the limitations of office blood pressure monitoring alone and underscore the importance of ABPM in accurate risk stratification and treatment optimization in CKD patients. In the long term, this study may contribute to improved hypertension management strategies, early identification of high-risk blood pressure phenotypes, reduction in cardiovascular and renal complications, and formulation of evidence-based recommendations for routine use of ABPM in hospitalized CKD patients.

This observational cross-sectional study was conducted among hospitalized patients with chronic kidney disease admitted to the general medicine wards of Government Medical College, Kozhikode. The study period extended from 1st January 2022 to 31st December 2022. All patients aged more than 12 years who were diagnosed with chronic kidney disease as per KDIGO 2012 guidelines and who provided informed consent were eligible for inclusion. Patients with acute kidney injury, those undergoing maintenance hemodialysis, post-renal transplant recipients, pregnant patients, and individuals unwilling to participate were excluded from the study. The sample size was calculated based on a previously published study evaluating the clinical utility of 24-hour ambulatory blood pressure monitoring in hospitalized CKD patients, which reported a prevalence of resistant hypertension of 39.6%. Using the formula 4pq/d² with an allowable error of 10%, the minimum required sample size was calculated to be 95. Due to logistical constraints and availability of eligible participants during the study period, a total of 88 patients were included in the final analysis. After enrollment, a detailed clinical evaluation was performed for all participants, including comprehensive history taking, general and systemic examination, anthropometric measurements, and routine laboratory investigations. Body mass index was calculated for all patients. Office blood pressure was measured using a mercury sphygmomanometer following standard guidelines. Two readings were obtained at an interval of five minutes in both upper limbs, and the average of these readings was recorded as the office or clinic blood pressure. All participants subsequently underwent 24-hour ambulatory blood pressure monitoring using a validated ABPM device. The appropriately sized cuff was applied to the non-dominant arm, and the monitoring unit was secured at waist level using belts. Blood pressure readings were recorded automatically at preset intervals throughout the day and night. The recorded data were downloaded and analyzed using Easy ABPM software. An ABPM recording was considered technically satisfactory if it had more than 14 valid daytime readings and more than 7 valid nighttime readings, with at least 70–80% of total readings being valid. Ambulatory blood pressure monitoring was performed free of cost for all study participants using the departmental facility. Ambulatory blood pressure parameters analyzed included mean daytime and nighttime systolic and diastolic blood pressure, blood pressure load, hyperbaric index, percent time elevation, nocturnal dipping status, and circadian blood pressure pattern. Hypertension phenotypes such as sustained hypertension, masked hypertension, white-coat hypertension, and resistant hypertension were identified based on standard definitions using combined office and ambulatory blood pressure values. Resistant hypertension was defined as uncontrolled blood pressure despite the use of three or more antihypertensive medications at optimal doses, including one diuretic. Data were entered and analyzed using the Statistical Package for the Social Sciences (SPSS) software version 19.0 for Windows. Quantitative variables were expressed as mean and standard deviation, while qualitative variables were presented as frequencies and percentages. The study was conducted after obtaining approval from the Institutional Research Committee and Institutional Ethics Committee of Government Medical College, Kozhikode. Written informed consent was obtained from all participants prior to inclusion in the study. Confidentiality of patient information was maintained throughout the study, and participation was entirely voluntary, with patients having the right to withdraw at any stage without affecting their standard medical care.

A total of 88 hospitalized patients with chronic kidney disease were included in the study, with a male predominance (60.2%) and a mean age of 57.41 ± 13.96 years. The majority of patients belonged to the 50–59 years age group. Comorbidities were highly prevalent, observed in 92.0% of the study population, with hypertension being the most common comorbidity (76.1%), followed by diabetes mellitus (45.5%) and coronary artery disease (20.5%). Most patients had advanced kidney disease, with 50.0% in stage 4 and 27.3% in stage 5 CKD. The mean serum creatinine and estimated glomerular filtration rate of the study population were 3.49 ± 1.77 mg/dL and 24.10 ± 13.03 mL/min/1.73 m², respectively.

Ambulatory blood pressure monitoring identified a higher prevalence of hypertension compared to office blood pressure measurement, with 80.7% of patients being hypertensive on ABPM as against 76.1% on office BP. A substantial proportion of patients classified as normotensive on office BP were found to have hypertension on ambulatory monitoring, indicating the presence of masked hypertension. Resistant hypertension was observed in 34.1% of the total study population and in 44.7% of hypertensive patients, with prevalence increasing progressively with advancing stages of CKD and reaching a maximum in stage 5 disease.

Analysis of ambulatory blood pressure parameters revealed that mean office systolic and diastolic blood pressure values were consistently higher than corresponding mean ambulatory values across all stages of CKD. Daytime and nighttime ABPM comparisons showed a progressive reduction in the normal day–night blood pressure difference with worsening CKD, indicating a shift toward abnormal circadian BP patterns. Nocturnal non-dipping pattern was highly prevalent, observed in 73.9% of patients, with the proportion of non-dippers increasing from stage 3 to stage 5 CKD. All patients with resistant hypertension demonstrated a non-dipping blood pressure pattern.

Advanced ambulatory indices showed a significantly higher nocturnal blood pressure burden. Nighttime hyperbaric index and percent time elevation were markedly higher than daytime values, particularly in stages 4 and 5 CKD, indicating increased nocturnal BP load. These abnormalities were more pronounced among patients with resistant hypertension, who demonstrated substantially elevated nighttime hyperbaric index and percent time elevation compared to the overall study population.

Target organ damage was common in the study population, with left ventricular hypertrophy present in 44.5% and hypertensive retinopathy in 37.5% of patients. The prevalence of target organ damage was significantly higher among patients with resistant hypertension, with evidence of left ventricular hypertrophy in 90% and retinopathy in 50% of resistant hypertension cases, highlighting the strong association between ambulatory BP abnormalities, resistant hypertension, and end-organ involvement.

Table 1: Demographic and Clinical Profile of the Study Population (n = 88)

Table 2: Distribution of Study Population According to Stage of CKD and Renal Function

Table 3: Blood Pressure Phenotypes Identified by Office BP and ABPM (n = 88)

Table 4: ABPM-Derived Outcomes and Target Organ Damage in the Study Population

Figure 1: Distribution of Blood Pressure Phenotypes by ABPM

Figure 2: Prevalence of Nocturnal Non- Dipping Pattern Across CKD Stages

In this study, the study population showed a male predominance (60.2%) with a mean age of 57.41 ± 13.96 years, reflecting the typical demographic profile of hospitalized CKD cohorts where older age and male predominance are frequently reported. Similar CKD-ABPM cohorts discussed in the literature generally report mean ages in the mid-50s to early-60s range with male proportions commonly around 55–70%, indicating that the demographic profile of this study is comparable to previously reported populations evaluated using ambulatory BP techniques in CKD settings [13].

A key observation of this study was that hypertension detection was higher on ABPM (80.7%) than on office BP (76.1%), suggesting that clinic measurements underestimated true BP burden in a subset of patients. Comparable studies have shown that ABPM identifies a higher prevalence of hypertension than OBPM, often by approximately 4–12% depending on the population and thresholds used. This aligns with the concept that ABPM improves diagnostic accuracy by capturing out-of-office BP variability and revealing masked patterns not evident during clinical measurement [13,14]. Thus, the difference observed in this study (approximately 4.6% higher detection on ABPM) is consistent with the direction and magnitude described in prior CKD-ABPM observations [13].

Regarding resistant hypertension, this study reported a prevalence of 34.1% overall and 44.7% among hypertensive patients. In comparative literature, resistant hypertension among CKD patients is often reported in the range of approximately 20–40% overall, and may approach 40–50% among those already classified as hypertensive or those with advanced CKD. Therefore, the burden of resistant hypertension in this study falls toward the higher end of what is typically reported, which is clinically plausible given that the participants were hospitalized CKD patients with a high proportion in stage 4 and stage 5 disease [15,16,20]. This supports the interpretation that ABPM in inpatient CKD populations can uncover clinically important high-risk hypertensive phenotypes that need aggressive optimization.

This study also demonstrated that resistant hypertension increased with worsening CKD stage, reaching around 50% in stage 5 CKD. Prior studies and expert reviews consistently report that resistant hypertension becomes more prevalent as renal function declines, driven by sodium retention, volume expansion, arterial stiffness, sympathetic activation, and RAAS dysregulation. In comparative cohorts, stage-wise progression of resistant hypertension commonly shows relatively lower prevalence in stage 2–3 CKD and markedly higher prevalence in stage 4–5 CKD, often approaching 35–55% in end-stage or near end-stage renal disease (excluding dialysis) [15,16]. Hence, the stage-linked trend demonstrated in this study strongly matches expected pathophysiological and clinical patterns noted in the literature.

A major ABPM-derived outcome in this study was the high prevalence of nocturnal non-dipping, observed in 73.9% of participants, with non-dipping prevalence increasing from 64.7% in stage 3 to 75.0% in stage 4 and 87.5% in stage 5 CKD; notably, all resistant hypertension patients were non-dippers. Comparative studies in CKD populations frequently report non-dipping proportions in the range of approximately 50–80%, with higher rates in advanced CKD and in those with poor BP control or resistant hypertension. Therefore, the 73.9% non-dipping prevalence in this study is consistent with the upper spectrum of previous findings, and the progressive increase across CKD stages is in line with the established observation that circadian BP rhythm becomes increasingly abnormal with declining renal function [17,18]. Clinically, this supports the importance of targeting nocturnal hypertension and restoring physiological dipping patterns where possible.

The day–night ABPM comparisons in this study showed a progressive reduction in day–night BP differences with advancing CKD, indicating a transition toward nocturnal non-dipping. Similar patterns are reported across CKD-ABPM literature, where nocturnal BP fails to decline appropriately and, in some cases, becomes equal to or higher than daytime BP. This phenomenon is repeatedly linked to higher cardiovascular risk and accelerated renal function decline compared to patients with preserved dipping patterns [17,18]. Thus, the stage-linked reduction in dipping observed in this study offers clinically meaningful evidence of worsening BP rhythm abnormality in advanced CKD.

This study further evaluated ABPM burden indices, demonstrating that nighttime hyperbaric index and percent time elevation were higher than daytime values, especially in stage 4 and stage 5 CKD. Comparative ABPM studies emphasize that nocturnal BP load and nighttime BP burden are strong predictors of end-organ damage, often outperforming clinic BP in risk prediction. The observation in this study that nighttime BP burden indices worsen with CKD severity is consistent with prior work describing that nocturnal hypertension and sustained BP load contribute to myocardial remodeling and microvascular injury [13,18,19]. These findings strengthen the argument that ABPM provides more clinically actionable information than OBPM alone.

Target organ damage in this study was substantial, with LVH in 44.5% and retinopathy in 37.5% of the overall study population. Importantly, resistant hypertension patients showed markedly higher damage: LVH in 90% and retinopathy in 50%. Comparative literature consistently reports a strong relationship between ambulatory BP burden (especially nocturnal BP) and LVH, with LVH prevalence commonly around 30–60% in CKD cohorts and considerably higher in those with resistant hypertension or non-dipping patterns. The markedly elevated LVH prevalence among resistant hypertensives in this study (90%) is compatible with the concept that sustained pressure overload and nocturnal BP elevation are major determinants of structural cardiac damage [19,20]. Therefore, this study’s data reinforce that resistant hypertension in CKD represents not only uncontrolled BP but also a high-risk end-organ damage phenotype requiring intensified monitoring and tailored therapy.

Overall, when this study is compared with previous ABPM-based CKD literature, the direction and magnitude of key outcomes—higher hypertension detection on ABPM than OBPM, high prevalence of resistant hypertension, progressive rise of resistant hypertension with CKD stage, high non-dipping prevalence with worsening CKD, and greater target organ damage in resistant hypertension—are consistent with established evidence. The present study adds practical inpatient-level data supporting ABPM as a clinically valuable tool for identifying masked patterns, confirming true resistant hypertension, and revealing nocturnal BP burden that correlates with target organ damage and advancing CKD stage [13–20].

This study demonstrates that 24-hour ambulatory blood pressure monitoring provides superior and clinically relevant information compared to office blood pressure measurement in hospitalized patients with chronic kidney disease. ABPM identified a higher prevalence of hypertension, detected masked and white-coat hypertension, and accurately characterized resistant hypertension, which was found to be common, particularly in advanced stages of CKD. A high burden of nocturnal non-dipping pattern, elevated nighttime blood pressure load, hyperbaric index, and percent time elevation were observed, with all resistant hypertension patients exhibiting non-dipping status. These abnormal ambulatory BP patterns were strongly associated with increased prevalence of target organ damage, including left ventricular hypertrophy and hypertensive retinopathy. Overall, the findings highlight the important role of ABPM in improving blood pressure assessment, risk stratification, and management of hypertension in CKD patients. LIMITATIONS The study has certain limitations that should be acknowledged. Being a cross-sectional study, causal relationships between ambulatory blood pressure parameters and progression of CKD or target organ damage could not be established. The study was conducted in a single tertiary care center with a relatively small sample size, which may limit the generalizability of the findings to the broader CKD population. ABPM was performed during hospitalization, and BP patterns may have been influenced by acute illness, hospital environment, and medication adjustments. Additionally, long-term cardiovascular and renal outcomes were not assessed, and follow-up ABPM recordings were not available to evaluate the impact of BP pattern correction on clinical outcomes. RECOMMENDATIONS Based on the findings of this study, routine use of

1. KDIGO Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1–150.
2. Mills KT, Xu Y, Zhang W, et al. A systematic analysis of worldwide population-based data on the global burden of chronic kidney disease. Lancet. 2015;395:709–733.
3. Agarwal R, Sinha AD. Cardiovascular protection with antihypertensive drugs in dialysis patients. Hypertension. 2009;53:860–866.
4. Varma PP. Prevalence of chronic kidney disease in India – Where are we heading? Indian J Nephrol. 2015;25:133–135.
5. Pickering TG, Davidson K, Gerin W, Schwartz JE. Masked hypertension. Hypertension. 2002;40:795–796.
6. O’Brien E, Parati G, Stergiou G, et al. European Society of Hypertension position paper on ambulatory blood pressure monitoring. J Hypertens. 2013;31:1731–1768.
7. Agarwal R, Andersen MJ. Prognostic importance of ambulatory blood pressure recordings in patients with chronic kidney disease. Kidney Int. 2006;69:1175–1180.
8. Minutolo R, Gabbai FB, Borrelli S, et al. Changing the timing of antihypertensive therapy to reduce nocturnal blood pressure in CKD. Hypertension. 2007;50:949–955.
9. Kario K, Pickering TG, Matsuo T, et al. Stroke prognosis and abnormal nocturnal blood pressure falls in older hypertensives. Hypertension. 2001;38:852–857.
10. Calhoun DA, Jones D, Textor S, et al. Resistant hypertension: diagnosis, evaluation, and treatment. Hypertension. 2008;51:1403–1419.
11. Bobrie G, Chatellier G, Genes N, et al. Cardiovascular prognosis of masked hypertension detected by blood pressure self-measurement in elderly treated hypertensive patients. JAMA. 2004;291:1342–1349.
12. Salarge SB, Ansari NNA, Mali VS. Clinical utility of 24-hour ambulatory blood pressure monitoring in hospitalized patients with chronic kidney disease. J Assoc Physicians India. 2021;69:11–15.
13. Agarwal R, Andersen MJ. Prognostic importance of ambulatory blood pressure recordings in patients with chronic kidney disease. Kidney Int. 2006;69:1175–1180.
14. Pickering TG, Davidson K, Gerin W, Schwartz JE. Masked hypertension. Hypertension. 2002;40:795–796.
15. Calhoun DA, Jones D, Textor S, et al. Resistant hypertension: diagnosis, evaluation, and treatment. Hypertension. 2008;51:1403–1419.
16. Sarafidis PA, Bakris GL. Resistant hypertension: an overview of evaluation and treatment. J Am Coll Cardiol. 2008;52:1749–1757.
17. Minutolo R, Gabbai FB, Borrelli S, et al. Changing the timing of antihypertensive therapy to reduce nocturnal blood pressure in CKD. Hypertension. 2007;50:949–955.
18. Kario K, Pickering TG, Matsuo T, et al. Stroke prognosis and abnormal nocturnal blood pressure falls in older hypertensives. Hypertension. 2001;38:852–857.
19. Agarwal R. Ambulatory blood pressure and cardiovascular outcomes in chronic kidney disease. Semin Nephrol. 2007;27:538–543.
20. Salarge SB, Ansari NNA, Mali VS. Clinical utility of 24-hour ambulatory blood pressure monitoring in hospitalized patients with chronic kidney disease. J Assoc Physicians India. 2021;69:11–15.