1. Association of hypertension with risk factors & hypertension related behavior among the aboriginal Nicobarese tribe living in Car Nicobar Island, India Sathya Prakash Manimunda, Attayuru Purushottaman Sugunan, Vivek Benegal, Nagalla Balakrishna, Mendu Vishnuvardhana Rao & Kasturi S. Pesala Indian J Med Res 133, March 2011, pp 287-293

2. Learning objective To understand cross sectional study.

3. Introduction Hypertension is one of the important public health challenges worldwide because of its high frequency and concomitant risks of cardiovascular and kidney disease. Leading risk factor for mortality. Ranked third as a cause of disability-adjusted life-years. The National Nutrition Monitoring Bureau (NNMB) has estimated the prevalence of hypertension among the rural adult (aged 18 and above) population of India to be 25 per cent during 2004-2005. Prevalence of hypertension among tribes in the range of 10-35 per cent Isolated studies carried out in these populations like among Lepchas of Sikkim Himalayas, tribes of Andhra Pradesh, Gujarat, and Orissa have documented the hypertension prevalence in the range of 15 to 42 per cent

4. Objective of the study To estimate the prevalence of hypertension, the association, and risk estimates of established risk factors of hypertension, and the awareness levels and compliance with medication advice, within the Nicobarese tribes people living in Car Nicobar Island.

5. Material and methods: Study design: Cross sectional study. Study duration: September 2007 to April 2009. (September 2007 to November 2007. Repeat survey - March 2009 to April 2009.) Sampling: 2 stage design. (1 st stage – Random selection of 40 out of 308 tuhets from 15 villages. 2 nd stage - All subjects aged ≥18 yr in selected tuhet were investigated. ) Study area: Study subject: 975 of 1270 eligible (Response rate of 76.8%) Nicobarese aged ≥ 18 yr were investigated.

6. Table I. Prevalence of hypertension among Nicobarese population Variable (n)Subcategory, n (%)Hypertensive, n (%) [95% CI] Sex (975)Male, 424 (43.5)215, (50.7) [44.0-57.4 ] Female, 551(56.5)277, (50.3) [ 44.4-56.2] Age (975) (yr)18-29<, 270 (27.7)78, (28.9) [18.8-38.9] 30-39<, 251 (25.7)109, (43.4) [34.1-52.7] 40-49<, 166 (17.0)100, (60.2) [50.6-69.8] 50-59<, 152 (15.6)105, (69.1) [60.3-77.9] ≥60, 136 (13.9)100, (73.5) [64.8-82.2] Education (824)No-education,244 (29.6)146, (59.8) [51.8-67.8] 1-5 yr, 139 (16.9)77, (55.4) [44.3-66.5] 6-10 yr, 357 (43.3)160, (44.8) [37.1-52.5] College, 84 (10.2)27, (32.1) [14.5-49.7] Tobacco consumption (831)No, 100 (12.0)48, (48.0) [33.9-62.1] Yes++, 731 (88.0)363, (49.7) [44.6-54.8] Alcohol consumption (831)No, 371 (44.6)168, (45.3) [37.8-52.8] Yes, 460 (55.4)243, (52.8) [46.5-59.1]

7. Table I. Prevalence of hypertension among Nicobarese population… Variable (n)Subcategory, n (%)Hypertensive, n (%) [95% CI] KF score category (717)≤ 3, 483 (67.4)234, (48.4) [42.0-54.8] 4 – 6, 210 (29.3)111, (52.90 [43.6-62.2] ≥7, 24 (3.3)11, (45.8) [16.4-75.2] QF value category (458)≤ 72 (50th percentile), 241 (52.6)127, (52.7) [44.0-61.4] > 72 (> 50th percentile), 217 (47.4) 113, (52.1) [42.9-61.3] AUDIT score category (451)< 8, 347 (76.9)185, (53.3) [46.1-60.5] 8 – 15, 84 (18.6)45, (53.6) [39.0-68.2] 16 – 19, 10 (2.2)5, (50.0) [6.2-93.8] ≥ 20, 10 (2.2)3, (30.0) [-] Nutritional status (667)Thinness, 34 (5.0)11, (32.4) [4.7-60.0] Normal, 387 (58.0)159, (41.1) [30.5-48.7] Overweight, 172 (25.8)102, (59.3) [49.8-68.8] Obese, 74 (11.0)62, (83.3) [74.0-92.6]

8. Table II. Association of hypertension with various variables in the equation VariableBivariate analysis Odds Ratio (OR)95% CIP value Age (yr)* 18- 30 (Ref.)1.0 ≥606.834.30-10.86<0.001 50-595.493.56-8.48<0.001 40-493.732.48-5.60<0.001 30-391.881.31-2.71=0.001 Education** College (Ref.)1.0 Illiterate3.141.86-5.31<0.001 1-5 yr2.621.48-4.62=0.001 6-10 yr1.711.03-2.83=0.03 Alcohol No (Ref.)1.0 Yes1.351.02-1.78=0.03 BMI Normal (Ref.)1.0 Overweight/obese2.862.05-4.0<0.001 Thinness0.680.32-1.44=0.32

9. Table III. Multiple Logistic Regression (MLR)* analysis VariableMLR analysis Odds Ratio (OR)95% CIP value Age 18- 30 (Reference)1.0 ≥608.744.56-16.73<0.001 50-598.174.37-15.29<0.001 40-494.392.43-7.93<0.001 30-391.661.00-2.75=0.04 Body mass index (BMI) Normal (Ref.)1.0 Overweight/obese4.102.72-6.19<0.001 Thinness0.290.11-0.79=0.01

10. What was known earlier? StudyPrevalanceMalesfemales Lepchas of Sikkim Himalayas -30.77%25.77% NNMB25%-- 2001 census47.2%-- Present study50.5%50.7%50.3%

11. Discussion Prevalence of hypertension (50.5%) among Nicobarese was high and was much more than the rural and urban populations in India. Usage of tobacco (88%) and alcohol (54%) was very high among Nicobarese but it did not add to the risk of hypertension. The association between smokeless tobacco use and risk of hypertension lacks evidence. The prevalence of overweight/obesity (37%) was also high among Nicobarese compared to rest of India. Poor awareness (12%), treatment (0.01%), and control (1 of 492) with extremely poor adherence to therapies (0.01%).

12. Limitation of study The lifestyle risk factors among the Nicobarese community were not estimated. Though it was the target of the study to get the data of risk factors from all 975 subjects whose BP was measured but it could not be achieved because of various socio-cultural beliefs of the community. Those who had gone to forest, fishing or out of the island (predominantly males) for employment opportunities were missed. Diagnosis was made only on one reading of blood pressure. Incomplete follow up data.

13. Conclusion High prevalence of hypertension among Nicobarese tribal population. Nutritional transition and gene – environment interaction is blamed for high prevalence of hypertension in the recent times among marginalized, poor, and tribal communities. Among Nicobarese this needs research to decipher the exact dynamics.