Risk of progression to hypertension from prehypertension and normal blood pressure: Results from a prospective cohort study among industrial workers in Kerala, India

Background: In India, studies exploring the incidence rate of hypertension (HTN) are limited particularly among industrial workers. We estimated the incidence rate of HTN among industrial workers with and without pre-HTN during a 2-year follow period and the factors associated with incident HTN among industrial workers in Kerala, India. Materials and Methods: A total of 326 industrial workers (mean age: 51 years, men: 76%), from two major industries in the state, enrolled at baseline were followed up at 2 years. All participants completed a structured interview schedule and had blood pressure (BP) and anthropometry measured using standard protocol. Results: Among the total workers, 36.5% were hypertensive, 39.3% were prehypertensive, and 24.2% had normal BP at baseline. At 2-year follow-up, 49.1% were hypertensive, 30.4% were prehypertensive, and 20.6% had normal BP. During follow-up, 19.8% of the 207 baseline nonhypertensives developed HTN providing an incidence rate of 9.9%/year (men: 10.7% and women: 7.6%). Incidence of HTN among ≥50 years was 11.4% compared to 9.0% among <50 years. Among the 79 workers with normal BP at baseline, 31.6% progressed to pre-HTN and 13.9% developed HTN, and among the 128 prehypertensives, 23.4% developed HTN at year 2. The odds of progressing to HTN from pre-HTN was two times higher compared to those from normal BP. Conclusion: The findings of this study indicated a higher risk for prehypertensive to develop HTN. Efforts should be made to prevent or delay the progression to HTN focusing on prehypertensives with frequent follow-up.