Opportunistic screening for hypertension: what does it say about the true epidemiology?

This study aimed to assess the reliability of opportunistic screening programs in estimating the prevalence, treatment, and control rate of hypertension in the general population. Two recent epidemiological surveys obtained data on hypertension in the adult general population in Greece. The EMENO (2013-2016) applied a multi-stage stratified random sampling method to collect nationwide data. The MMM (2019) collected data through opportunistic (voluntary) screening in five large cities. Hypertension was defined as blood pressure (BP) ≥ 140/90 mmHg (single occasion; average of 2nd-3rd measurement; electronic devices) and/or use of antihypertensive drugs. Data from a total of 10,426 adults were analyzed (EMENO 4,699; MMM 5,727). Mean age (SD) was 49.2 (18.6)/52.7 (16.6) years (EMENO/MMM, p < 0.001), men 48.6/46.5% (p < 0.05) and body mass index 28.2 (5.7)/27.1 (5.0) kg/m2 (p < 0.001). The prevalence of hypertension in ΕΜΕΝΟ/MMM was 39.6/41.6% (p < 0.05) and was higher in men (42.7/50.9%, p < 0.001) than in women (36.5/33.6%, p < 0.05). Among hypertensive subjects, unaware were 31.8/21.3% (EMENO/MMM, p < 0.001), aware untreated 2.7/5.6% (p < 0.001), treated uncontrolled 35.1/24.8% (p < 0.001), and treated controlled 30.5/48.3% (p < 0.001). In conclusion, the prevalence of hypertension was similar with random sampling (EMENO) and opportunistic screening (MMM). However, opportunistic screening underestimated the prevalence of undiagnosed hypertension and overestimated the rate of hypertension treatment and control. Thus, random sampling national epidemiological studies are necessary for assessing the epidemiology of hypertension. Screening programs are useful for increasing awareness of hypertension in the general population, yet the generalization of such findings should be interpreted with caution.