What is the incidence of renal artery stenosis in the Indian population, particularly in those with hypertension and diabetes?

Incidence of Renal Artery Stenosis in Indian Population

Limited Direct Indian Data Available

Direct epidemiological data on renal artery stenosis (RAS) incidence in the Indian population is extremely limited, but extrapolation from high-risk populations and autopsy studies suggests rates of 8-33% in hypertensive diabetic patients. 1, 2

Prevalence in High-Risk Indian Populations

Hypertensive Patients with Diabetes

• In diabetic patients with hypertension and/or renal impairment, RAS prevalence reaches 33%, based on prospective MRA screening studies 2
• Autopsy studies demonstrate RAS in 8.3% of all diabetic patients (95% CI, 6.8-9.8%), with an odds ratio of 3.5 compared to non-diabetics 1
• The frequency increases to 10.1% in diabetic patients with concurrent hypertension 1
• Bilateral RAS occurs in 43% of diabetic patients with RAS, compared to 30% in non-diabetics 1

Hypertensive Patients Undergoing Cardiac Catheterization

• More than 20% of hypertensive patients undergoing cardiac catheterization have unilateral or bilateral stenoses ≥70% 3
• Screening angiography during coronary procedures reveals significant RAS (>50% stenosis) in 15-30% of consecutive patients 3
• In patients with established coronary artery disease, incidental RAS climbs to 22% 3

Resistant Hypertension Population

• Among patients ≥50 years referred to hypertension centers, 12.7% have secondary hypertension, with renovascular disease accounting for 35% of these cases 3
• Studies of treatment-resistant hypertension reveal high prevalence of previously unrecognized renovascular disease, particularly in older patient groups 3

Risk Factors Predicting Higher Incidence in Indians

Age-Related Risk

• Significant RAS is found more frequently in patients older than 60 years with an odds ratio of 4.76 (95% CI: 2.08-10.86) 4
• The likelihood of atherosclerotic RAS increases substantially with age 3

Comorbid Atherosclerotic Disease

• Coronary artery disease, history of myocardial infarction, or stroke significantly increases the chance of RAS detection 4
• In patients with peripheral arterial disease (PAD), 33-39% have significant RAS (>50% stenosis) 3
• The extent of coronary artery disease is the strongest predictor of concomitant RAS 3

Diabetes Mellitus

• Non-insulin-dependent diabetes mellitus increases the risk of RAS by 3.5-fold 1
• Diabetes predicts lack of blood pressure control and treatment resistance 3

Clinical Implications for Indian Population

High-Risk Screening Candidates

• Screen for RAS in Indian patients with:
  • Resistant hypertension requiring ≥3 antihypertensive medications 3
  • Diabetes mellitus with hypertension and/or renal impairment 2, 1
  • Known atherosclerotic disease, especially peripheral arterial disease 3
  • Unexplained renal insufficiency 3
  • History of "flash" or episodic pulmonary edema with preserved systolic function 3

Underdiagnosis Problem

• RAS goes undetected before autopsy in 93% of cases, indicating massive underdiagnosis in clinical practice 1
• This suggests the true incidence in Indian populations may be substantially higher than clinically recognized 1

Diagnostic Approach

Noninvasive Screening

• Duplex ultrasound, MRA, CT angiography, and renal scintigraphy have good test characteristics, but true positive and negative predictive values vary with institutional expertise 3
• MRA is highly sensitive but has low specificity, often overestimating stenosis severity 3
• Negative imaging studies warrant additional examinations in patients with high clinical suspicion 3

Critical Pitfall to Avoid

Never assume RAS is absent in Indian patients with diabetes, hypertension, and atherosclerotic disease based solely on lack of classic clinical clues—the condition is frequently asymptomatic and underdiagnosed. 1, 3