Prevalence and Risk Factors Associated with Chronic Kidney Disease in Adults over 40 Years: A Retrospective Cross Sectional Study

Chronic kidney disease (CKD) is a major global public health concern, characterized by the progressive loss of kidney function over time. It is a leading cause of morbidity and mortality, particularly among older adults, with significant implications for healthcare systems worldwide [1]. CKD is often asymptomatic in its early stages, leading to under diagnosis and delayed intervention, which increases the risk of progression to end-stage renal disease (ESRD) requiring dialysis or transplantation [2]. The global prevalence of CKD is estimated at 10–15%, with higher rates observed in aging populations and those with comorbid conditions such as diabetes and hypertension [3]. In low- and middle-income countries, including Iraq, the burden of CKD is exacerbated by limited healthcare resources, poor disease awareness, and inadequate preventive measures [4]. In Iraq, particularly in urban areas like Baghdad, the rising prevalence of non-communicable diseases (NCDs) such as diabetes mellitus (DM) and hypertension (HTN) has contributed to an increased incidence of CKD [5].

Adults over 40 years are at higher risk due to age-related decline in kidney function and the cumulative effects of metabolic and cardiovascular risk factors [6]. Furthermore, lifestyle factors, including poor dietary habits, physical inactivity, and smoking, further accelerate kidney damage in this population [7]. Despite these risks, there is limited recent data on CKD prevalence and associated risk factors among adults in Baghdad, highlighting the need for updated epidemiological studies to inform public health strategies [8]. The pathogenesis of CKD involves multiple interrelated factors, including glomerular hypertension, chronic inflammation, and oxidative stress, which are often driven by underlying conditions such as diabetes and hypertension [9]. Diabetes, in particular, is the leading cause of CKD globally, with diabetic kidney disease (DKD) accounting for nearly 40% of all CKD cases [10]. Hypertension, another major contributor, causes renal vascular damage, leading to glomerulosclerosis and tubulointerstitial fibrosis [11].

Other significant risk factors include obesity, dyslipidemia, cardiovascular disease (CVD), and a family history of kidney disease [12]. Environmental and socioeconomic factors, such as limited access to healthcare, poor medication adherence, and exposure to nephrotoxic agents, further compound the risk [13]. In Baghdad, the healthcare system faces challenges in early CKD detection and management due to fragmented primary care services and a lack of widespread screening programs [14]. Many patients present late with advanced CKD, leading to poorer outcomes and higher treatment costs [15]. Additionally, cultural and behavioral factors, such as high salt intake and low water consumption, may contribute to kidney dysfunction in this population [16]. Given these challenges, understanding the local epidemiology of CKD is essential for developing targeted interventions to reduce disease burden and improve renal health outcomes [17]. This study aims to determine the prevalence of CKD and identify associated risk factors among adults aged 40 years and above in Baghdad through a retrospective cross-sectional analysis.

Study Design and Population

This study employed a retrospective cross-sectional design to assess the prevalence of chronic kidney disease (CKD) and its associated risk factors among adults aged 40 years and older in Baghdad, Iraq. The study utilized electronic health records (EHRs) from three major tertiary hospitals in Baghdad (Al-Kindy Teaching Hospital, Baghdad Teaching Hospital, and Al-Imamein Al-Kadhimein Medical City) between January 2020 and December 2023.

Sample Size Calculation

The sample size was determined using the single proportion formula for prevalence studies:

Where:
Z = 1.96 (95% confidence level)
p = 15% (estimated CKD prevalence based on regional data) [8].
d = 3% (margin of error)

The minimum required sample size was 544 participants, but to account for missing data and improve robustness, 1,200 records were included.

Inclusion Criteria

a) Adults aged ≥40 years.
b) Patients with at least one serum creatinine measurement during the study period.
c) Availability of demographic and clinical data (e.g., age, sex, comorbidities).

Exclusion Criteria

a) Patients with end-stage renal disease (ESRD) on dialysis.
b) Pregnant women (due to physiological changes in kidney function).
c) Incomplete medical records (missing key variables such as blood pressure or HbA1c).

Data Collection and Measurements Data Sources

a) Hospital EHRs: Demographic data, medical history, laboratory results.
b) Laboratory databases: Serum creatinine, urine albumin-tocreatinine ratio (UACR).
c) Pharmacy records: Medication use (e.g., antihypertensives, antidiabetics).

Kidney Function Assessment Estimated Glomerular Filtration Rate (eGFR)

a) Calculated using the CKD-EPI 2021 equation [18].

b) CKD Stages (KDIGO 2023 criteria):
a) Stage 1: eGFR ≥90 mL/min/1.73m² + albuminuria (UACR ≥30 mg/g)
b) Stage 2: eGFR 60–89 + albuminuria
c) Stage 3a: eGFR 45–59
d) Stage 3b: eGFR 30–44
e) Stage 4: eGFR 15–29
f) Stage 5: eGFR <15

Albuminuria Measurement

a) Urine Albumin-to-Creatinine Ratio (UACR) from a random urine sample
b) Categories:
a) Normal: <30 mg/g.
b) Moderately increased (microalbuminuria): 30–300 mg/g.
c) Severely increased (macroalbuminuria): >300 mg/g.

Assessment of Risk Factors

The following modifiable and non-modifiable risk factors were evaluated:

Hypertension (HTN)

Defined as Systolic BP ≥140 mmHg or Diastolic BP ≥90 mmHg [11]. Self-reported diagnosis or use of antihypertensive medications.

Diabetes Mellitus (DM)

Defined as fasting glucose ≥126 mg/dL or HbA1c ≥6.5% [19]. Self-reported diagnosis or use of anti-diabetic drugs.

Obesity

Body Mass Index (BMI):
a) Normal: 18.5–24.9 kg/m².
b) Overweight: 25–29.9 kg/m².
c) Obese: ≥30 kg/m².

Smoking Status

a) Current smoker: Any tobacco use in the past 6 months. b) Former smoker: Quit >6 months ago. c) Never smoker: No history of smoking.

Dyslipidemia

Total cholesterol ≥200 mg/dL or LDL ≥130 mg/dL [20].

Cardiovascular Disease (CVD)

History of coronary artery disease (CAD), stroke, or heart failure.

Family History of CKD

First-degree relative with CKD or ESRD.

Medication Use

NSAIDs, nephrotoxic drugs (e.g., aminoglycosides, contrast agents).

Statistical Analysis Descriptive Statistics

a) Categorical variables: Frequency (%).
b) Continuous variables: Mean ± SD or median (IQR).

Prevalence Calculation

a) Overall CKD prevalence (Stages 1–5).
b) Stratified by age, sex, and comorbidities.

Risk Factor Analysis

a) Univariate logistic regression: Assess crude associations between risk factors and CKD.
b) Multivariate logistic regression: Adjusted for age, sex, BMI, and comorbidities.
c) Odds ratios (OR) with 95% confidence intervals (CI).

Statistical Software

a) SPSS v28 and R v4.3 for analysis.
b) P-value <0.05 considered statistically significant.

Ethical Considerations

a) Approval obtained from Baghdad Health Directorate Ethics Committee.
b) Patient data anonymized (no identifiable information used).

The overall CKD prevalence was 18.7%, with a significant age-dependent increase: 29.8% in adults ≥60 years vs. 9.2% in those aged 40–49 (p<0.001). Men had a slightly higher prevalence than women (20.1% vs. 16.9%), though this difference was not statistically significant (p=0.12). Urban residents showed marginally higher CKD rates (19.3%) compared to rural areas (16.4%), potentially reflecting better diagnostic access or higher exposure to risk factors like processed diets and pollution. These findings align with global trends of rising CKD prevalence with age and urban city (Table 1). Hypertension (aOR=2.45) and diabetes (aOR=3.12) were the strongest independent predictors of CKD, consistent with their roles in glomerular damage (Alicic et al., 2024). Obesity (aOR=1.68) and smoking (aOR=1.52) also showed significant associations, likely due to their contributions to metabolic syndrome and endothelial dysfunction. Dyslipidemia (aOR=1.34) and family history (aOR=1.91) further compounded risk, suggesting genetic and lipid-mediated pathways in CKD progression. These findings underscore the need for integrated management of cardio metabolic risk factors in CKD prevention (Table 2).

The data shows a clear age-dependent progression of CKD severity, with advanced stages (3b-35) being 5-10 times more prevalent in adults ≥60 compared to those 40-49 (p<0.001). This highlights the cumulative effect of aging on kidney function decline and emphasizes the need for age-targeted screening (Table 3). The co-occurrence of HTN and DM was 2.6 times more likely in CKD patients (p<0.001), suggesting synergistic nephrotoxicity. Notably, isolated HTN was less prevalent in CKD patients, possibly indicating better blood pressure control in this group or survival bias (Table 4). While ACEi/ARB use increased with CKD severity (trend p=0.041), SGLT2 inhibitor use peaked in Stage 3 then declined, possibly due to late-stage contraindications. The significant decrease in NSAID use in advanced CKD (p=0.018) suggests better nephrotoxicity awareness (Table 5). Proteinuria (UACR>300mg/g) showed the strongest association with progression (HR=3.15), accounting for 42.5% of population risk. The PAR% analysis suggests that addressing just three modifiable factors (HTN, DM, proteinuria) could prevent ~75% of CKD progression cases (Table 6). Advanced CKD stages required 3-4 times more monitoring and had significantly lower medication adherence (p=0.003), highlighting both the healthcare burden and potential gaps in latestage management (Table 7).

Table 1:Prevalence of Chronic Kidney Disease (CKD) Among Adults Aged ≥40 Years in Baghdad (N=1,200).

Table 2:Adjusted Odds Ratios (aOR) for Risk Factors Associated with CKD (Multivariate Logistic Regression).

Table 3:CKD Stage Distribution by Age Group (N=1,200).

Table 4:Comorbidity Patterns in CKD vs Non-CKD Population.

Table 5:Medication Use Patterns in CKD Patients by Stage.

Table 6:Multivariate Analysis of CKD Progression Risk Factors.

Table 7:Healthcare Utilization by CKD Stage.

Our study reveals several critical findings about CKD epidemiology in Baghdad that both confirm and contrast with global patterns. The overall CKD prevalence of 18.7% (Table 1) exceeds rates reported in neighboring Gulf countries (15.2% in Kuwait) [21], but aligns closely with regional estimates from war-affected areas like Syria (19.1%) [22], suggesting conflict-related healthcare disruptions may contribute to this elevated burden. The striking age gradient we observed (29.8% in ≥60 vs 9.2% in 40–49-year-olds) mirrors global aging-related patterns [23], but the magnitude of difference is more pronounced than in European populations [24], potentially reflecting accelerated kidney aging in our population due to cumulative environmental and metabolic stressors. The sex disparity we identified (20.1% male vs 16.9% female prevalence) contrasts with most Western studies showing female predominance [25], but aligns with Middle Eastern reports [26]. This likely reflects regional gender differences in healthcare access, with Iraqi women facing greater barriers to routine screening [5]. Our urban-rural findings (19.3% vs 16.4%) differ from China’s rural-predominant pattern [27], possibly due to Baghdad’s unique urban risk factors including pollution and processed food consumption.

Table 2’s risk factor analysis reveals hypertension (aOR=2.45) and diabetes (aOR=3.12) as dominant drivers, consistent with global literature [1], but showing stronger associations than in high-income countries, likely due to suboptimal control rates [28]. The particularly high risk from proteinuria (UACR>300mg/g, HR=3.15 in Table 6) exceeds estimates from African cohorts [29], suggesting possible genetic or environmental modifiers in our population. The age-stratified analysis of CKD stages reveals a striking progression pattern, with advanced stages (3b-5) being 5-10 times more prevalent in adults ≥60 years (18.4%) compared to those aged 40-49 (2.1%, p<0.001), exceeding regional reports from Saudi Arabia and Iran [16,26]. This accelerated progression likely reflects cumulative exposure to multiple risk factors including uncontrolled hypertension (prevalence >60% in Iraqi elderly), poorly managed diabetes (mean HbA1c 8.7%), and environmental pollutants (Baghdad’s PM2.5 levels exceeding WHO limits by 7-9×), compounded by healthcare access barriers evidenced by delayed diagnosis (median 3.2 years in elderly vs 1.8 years in younger patients, p=0.003) and low screening rates (only 28% of early-stage patients had prior kidney testing) [14,28,30].

The disproportionate Stage 3a representation (7.2% in ≥60 vs 1.8% in 40-49) suggests accelerated aging-related nephron loss [18], while the relatively low Stage 5 prevalence (2.2% vs regional 3.8%) may indicate under-diagnosis or competing cardiovascular mortality [31]. These findings underscore the need for earlier screening (starting at age 45), age-specific management protocols, and environmental risk reduction strategies in Baghdad’s CKD control programs. Our comorbidity analysis (Table 4) shows striking HTN-DM synergy (58.9% co-prevalence in CKD patients), exceeding rates from Jordan (42.1) [32], and underscoring the need for integrated management. The medication patterns in Table 5 reveal critical gaps: ACEi/ARB use (62.1% in early stages) falls below KDIGO recommendations (2023) [24], while the paradoxical decline in SGLT2i use in advanced CKD (5.1% in Stage 4-5) reflects persistent safety concerns despite recent guideline updates (American Diabetes Association [ADA], 2023) [19]. The healthcare utilization patterns (Table 7) demonstrate a 3-4-fold increase in monitoring needs with progression, similar to Malaysian data [33], but with notably lower adherence rates (47% in Stage 4-5 vs 61% in Thailand [34].

This likely reflects Iraq’s fragmented referral system and medication affordability issues (World Health Organization [WHO], 2023) [35]. Several findings demand particular attention. First, the population attributable risks in Table 6 suggest that addressing just three factors (HTN, DM, proteinuria) could prevent 75% of progression cases - more impactful than in Western populations [36]. Second, the steep decline in NSAID use with advancing CKD (Table 5) indicates successful provider education about nephrotoxins, a rare positive finding compared to similar LMICs [13]. Our results contrast notably with recent Turkish data [37], showing better early-stage detection, suggesting Iraq’s screening programs are missing early intervention opportunities. However, they align closely with Egyptian findings [38], regarding comorbidity clustering, indicating regional consistency in CKD drivers. The comparison with global literature suggests that while CKD pathophysiology is universal, its manifestation in Baghdad reflects Iraq’s unique epidemiological transition - combining developing nation risk factors (infections, toxins) with industrialized nation comorbidities (diabetes, hypertension) amidst healthcare system challenges. This necessitates tailored solutions that adapt global best practices to local realities.

This study highlights a high prevalence (18.7%) of CKD among adults aged ≥40 years in Baghdad, with older age, hypertension, diabetes, and proteinuria emerging as the most significant risk factors. The findings align with global trends but reveal local challenges, including late diagnosis, suboptimal treatment adherence, and fragmented healthcare delivery. The strong association between CKD and cardio metabolic diseases underscores the need for integrated management strategies, while urban-rural disparities and gender differences suggest socioeconomic and cultural barriers to care.

This study has several important limitations that should be acknowledged. First, its retrospective cross-sectional design using hospital records may introduce selection bias by missing undiagnosed cases in the community and limits causal inference regarding risk factors. Second, reliance on single measurements of serum creatinine for eGFR calculation without cystatin C confirmation could lead to misclassification, particularly in elderly or malnourished patients. Third, the study lacked data on potentially important confounders such as detailed dietary patterns, medication adherence, and environmental exposures. Fourth, the sample was drawn from tertiary hospitals in Baghdad, which may not fully represent rural populations or those with limited healthcare access. Fifth, the COVID-19 pandemic during the study period (2020-2023) may have affected healthcare utilization patterns and disease detection rates. Additionally, medication use was assessed through prescription records rather than direct adherence monitoring. These limitations highlight the need for future prospective community-based studies incorporating more comprehensive risk factor assessments and direct measurements of kidney function to better understand CKD epidemiology in Iraq. Despite these constraints, the study provides valuable baseline data on CKD burden and associated factors in this understudied population.

To address the high burden of CKD in Baghdad, we recommend implementing a comprehensive strategy that includes (1) enhanced screening programs incorporating routine eGFR and UACR testing for high-risk groups, particularly in primary care settings; (2) optimized management of comorbidities through stricter blood pressure and glycemic control using nephron-protective medications like ACEi/ARBs and SGLT2 inhibitors, supported by multidisciplinary care teams; (3) healthcare system strengthening via EHR integration for better disease monitoring and primary care physician training on CKD management protocols; (4) public health interventions focusing on dietary salt/sugar reduction and targeted smoking cessation programs; and (5) establishment of a national CKD registry to facilitate longitudinal research and evidence-based policymaking, with particular attention to addressing urbanrural disparities and improving healthcare access for vulnerable populations. These integrated measures should be prioritized within Iraq’s NCD control programs to reduce the growing CKD burden through early detection, improved treatment adherence, and systematic healthcare delivery optimization.

None

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