Table 2.
Incidence and risk factors for hypertension.
| Variables | N | Un-adjusted incidence rate per 1000 p-y (95% CI) | Adjusted incidence rate per 1000 p-y (95% CI)∏ | Unadjusted RR, CI | Adjusted RR,CI (n = 6250) |
Adjusted RR,CI (without Karachi)Ⱡ (n = 4680) | Adjusted RR, CI (Missing co-variates imputed at baseline) |
|---|---|---|---|---|---|---|---|
| Overall | 8146 | 80.5 [76.3,85.0] | 74.6[70.5,79.1] | ||||
| City | |||||||
| Chennai | 3528 | 76.0[69.6,83.1] | 71.5[65.4,78.2] | 1 | 1 | 1 | 1 |
| Delhi | 2408 | 95.7[87.6,104.6] | 93.6[85.8,102.2] | 1.54‡[1.36,1.74] | 1.27** [1.09,1.47] | 1.21*[1.04,1.41] | 1.28***[1.12,1.47] |
| Karachi | 2210 | 70.4[63.3,78.3] | 69.0[62.0,76.9] | 1.16* [1.01,1.33] | 1.20 [1.00,1.44] | NA | 1.23* [1.05, 1.45] |
| Age groups, years | |||||||
| 20–24 | 718 | 28.6[21.1,38.7] | 26.8[19.2,38.6] | 1 | 1 | 1 | 1 |
| 25–34 | 2346 | 50.1[44.1,56.9] | 45.1[39.3,52.0] | 1.63**[1.12,2.36] | 1.38 [0.89,2.13] | 1.33 [0.76,2.35] | 1.37 [0.94, 2.00] |
| 35–44 | 2588 | 74.8[67.7,82.6] | 65.2[58.6,72.8] | 2.38ǂ[1.66,3.41] | 1.62*[1.05,2.48] | 1.65 [0.95,2.88] | 1.64** [1.13, 2.37] |
| 45–54 | 1530 | 113.9[102.5,126.5] | 110.1[98.9,122.8] | 3.99‡[2.78,5.71] | 2.35‡ [1.52,3.63] | 2.32‡ [1.33,4.06] | 2.42‡ [1.66,3.52] |
| 55–64 | 670 | 160.9[140.8,183.8] | 162.1 [143.2,184.3] | 5.97‡[4.15,8.61] | 3.44‡ [2.21,5.35] | 3.45‡ [1.95,6.09] | 3.46‡ [2.36,5.07] |
| 65−65 | 294 | 147.2[119.5,181.5] | 152.9[125.9,187.7] | 5.71‡[3.84,8.48] | 3.15‡ [1.96,5.06] | 3.38‡ [1.86,6.16] | 3.08‡ [2.04,4.65] |
| Sex | |||||||
| Female | 4627 | 70.9[65.7,76.5] | 65.4[60.3,71.1] | 1 | 1 | 1 | 1 |
| Male | 3519 | 93.1[86.3,100.5] | 92.3[85.3,99.9] | 1.43‡[1.28,1.60] | 1.08 [0.92,1.26] | 1.17 [0.98,1.40] | 1.05 [0.92, 1.21] |
| Education | |||||||
| ES1 | 1385 | 75.7[66.3,86.5] | 67.0[58.3,77.3] | 1 | 1 | 1 | 1 |
| ES2 | 2442 | 77.8[70.4,86.0] | 71.6[64.5,79.8] | 1.02 [0.85,1.22] | 1.15 [0.95,1.39] | 1.15 [0.93,1.44] | 1.13 [0.95, 1.34] |
| ES3 | 2672 | 80.8[73.4,88.8] | 75.1[68.0,83.2] | 1.04[0.87,1.24] | 1.19 [0.98,1.45] | 1.23 [0.99,1.54] | 1.14 [0.95, 1.36] |
| ES4 | 1647 | 88.3[78.8,99.0] | 85.8[76.3,97.0] | 1.24*[1.03,1.49] | 1.29*[1.05,1.60] | 1.25*[0.97,1.61] | 1.23* [1.02, 1.49] |
| BMI, kg/m2 | |||||||
| < 18.00 | 454 | 40.5[29.5,55.7] | 34.0[24.3,49.0] | 0.65*[0.45,0.94] | 0.73 [0.50,1.07] | 0.82[0.53,1.25] | 0.82 [0.60, 1.12] |
| 18.00−22.99 | 2010 | 59.1[52.1,67.1] | 54.3[47.6,62.2] | 1 | 1 | 1 | 1 |
| 23.00−24.99 | 1031 | 79.7[68.3,93.0] | 72.5[62.1,85.2] | 1.31**[1.07,1.61] | 1.14 [0.92,1.42] | 1.05 [0.82,1.34] | 1.10 [0.91, 1.34] |
| ≥25.00 | 3272 | 98.6[91.2,106.6] | 87.7[81.1,95.0] | 1.57‡[1.34,1.83] | 1.28*[1.04,1.59] | 1.18 [0.91,1.52] | 1.25* [1.03, 1.52] |
| Waist circumference, cm | |||||||
| Non obese | 3917 | 60.0[54.8,65.7] | 55.2[50.1,61.1] | 1 | 1 | 1 | 1 |
| Obese | 4229 | 99.4[92.9,106.3] | 89.5[83.4,96.1] | 1.63‡[1.44,1.84] | 1.04 [0.86,1.26] | 1.05 [0.84,1.32] | 1.06 [0.90, 1.27] |
| Tobacco use | |||||||
| Never users | 6326 | 75.8[71.2,80.8] | 70.4[65.8,75.3] | 1 | 1 | 1 | 1 |
| Ever users | 1820 | 96.6[87.1,107.1] | 96.5[86.9,107.5] | 1.41‡[1.24,1.59] | 1.08 [0.92,1.27] | 1.04 [0.86,1.26] | 1.09 [0.95, 1.26] |
| Current alcohol use | |||||||
| No | 7231 | 75.8[71.4,80.4] | 70.8[66.5,75.5] | 1 | 1 | 1 | 1 |
| Yes | 915 | 119.3[104.3,136.4] | 113.2[98.8,130.3] | 1.55‡[1.33,1.80] | 1.34** [1.10,1.62] | 1.25**[1.02,1.54] | 1.37‡ [1.15,1.63] |
| Physical Activity | |||||||
| Low | 811 | 92.9[79.6,108.5] | 85.0[72.8,100.0] | 1 | 1 | 1 | 1 |
| Medium | 2181 | 84.7[76.7,93.6] | 77.6[69.8,86.5] | 0.88[0.73,1.07] | 0.94 [0.76,1.16] | 1.01 [0.77,1.33] | 0.96 [0.80, 1.15] |
| High | 5154 | 76.5[71.3,82.1] | 72.3[67.1,78.0] | 0.76**[0.63,0.90] | 1.03 [0.85,1.26] | 1.00 [0.77,1.30] | 1.03 [0.86, 1.23] |
| Glycemic status | |||||||
| Normal | 2892 | 123.9[111.0,138.4] | 49.7[44.3,55.8] | 1 | 1 | 1 | 1 |
| Diabetes | 1282 | 83.5[76.4,91.1] | 119.2[106.9,133.2] | 2.39‡[2.04,2.80] | 1.27*[1.05,1.53] | 1.32* [1.06,1.64] | 1.22* [1.03, 1.44] |
| Pre-diabetes | 2977 | 54.4[48.7,60.8 | 77.3[70.7,84.8] | 1.56‡[1.34,1.80] | 1.12 [0.96,1.32] | 1.14 [0.94,1.39] | 1.09 [0.95, 1.26] |
| Parental history of hypertension | |||||||
| No | 6896 | 82.1[77.5,87.0] | 74.9[70.4,79.8] | 1 | 1 | 1 | 1 |
| Yes | 1250 | 71.9[62.2,83.2] | 73.2[62.9,85.6] | 0.97 [0.83,1.15] | 1.11 [0.93,1.32] | 1.20 [0.99,1.47] | 1.10 [0.93, 1.29] |
| eGFR, ml/min/1.73 m2 | |||||||
| > = 60 | 7137 | 77.8[73.3,82.5] | 73.3[69.0,78.0] | 1 | NA | 1 | NA |
| < 60 | 121 | 142.4[103.2,196.5] | 128.7[95.5,177.4] | 1.94‡[1.42,2.66] | 1.10 [0.69,1.74] | ||
| Baseline blood pressure levels, mmHg | |||||||
| Normal BP | 4420 | 38.0[34.1,42.3] | 35.7[31.8,40.3] | 1 | 1 | 1 | 1 |
| Pre-hypertension | 3726 | 131.1[123.1,139.6] | 129.4 [121.5,137.9] | 3.62‡ [3.17,4.14] | 2.95ǂ [2.53,3.45] | 3.3ǂ[2.74,4.04] | 2.90‡ [2.52,3.34] |
| Years of follow-up | 1.22**[1.08, 1.38] | 1.23** [1.06, 1.41] | 1.22* [1.04, 1.41] | 1.18* [1.04, 1.35] | |||
*p < 0.05, **P < 0.01, ‡p < 0.001, RR=relative risk ratio.
∏Adjusted for uneven response rate in different risk groups, Ⱡmodel includes serum creatinine based eGFR measurements from Delhi and Chennai (data are not available in Karachi). p-y = person years, ci = confidence interval, eGFR = estimated glomerular filtration rate, BMI = body mass index, ES1 = educational status (above graduates), ES2 = secondary school education, ES3 = primary school and above, ES4 = lower than primary or no formal education or illiterates.