The JNC VI recommends the use of diuretics or β-blockers as first line therapy in hypertension on the basis of the results of two meta-analyses.[22
] We found some differences in the studies included in these meta-analyses: Psaty et al. did not include some of the studies that were used by MacMahon et al., because of the use of multiple interventions, [24
] the use of drugs different than diuretic of β-blockers, [25
] or because the study directly compared diuretics to β-blockers.[27
] Furthermore, Psaty et al. included 3 studies that had not been published at the time when MacMahon et al. published their results.[28
] For these reasons, we used the trials included in the meta-analysis by Psaty et al. We were unable to retrieve information from a small study (n = 91) performed in Japan [31
] that was used by Psaty et al. The final number of studies considered was 16.[29
Table shows the inclusion and exclusion criteria in the trials considered. While most trials had advanced age as exclusion criteria, seven enrolled people aged > 70 years. The majority of these trials included people with diastolic hypertension, typically with diastolic blood pressure around 90 – 120 mmHg. Myocardial infarction was an exclusion criterion in 6 trials, stroke in 6 trials, HF in 8 trials, and renal failure in 9 trials.
The Adult Survey section of the NHANES III had information on 20,050 participants. About 23% of this population had a diagnosis of hypertension, and of these 11% had hypertension requiring treatment according to the recommendations of the JNC VI. The proportion of people with a diagnosis of hypertension but not included in our population because they had normal blood pressure was 17%. In this subgroup of people, 62% reported a prescription of an anti-hypertensive medication. In our study population, 4.1% had stage 2/3 hypertension with no other risk factors; 39.2% had stage 2/3 hypertension with at least one risk factor, 17.3% had high normal blood pressure and target organ damage or diabetes, 26.1% had stage 1 hypertension with target organ damage or diabetes, and 13.3% had stage 2/3 hypertension with target organ diseases or diabetes. The mean age was 63 years (range 17 – 90), 50% were women and 82% were white.
Table shows the proportion of the people with hypertension requiring drug treatment according to the JNC VI. The first column reports the percent of the total hypertensive population that would be eligible for each trial according to their age, gender and blood pressure levels. The second column reports the proportion of people that would have been excluded from the trials because of MI, stroke, HF, and renal impairment. Finally, we report the proportion of the hypertensive population that would potentially be enrolled in each trial. We observe a marked variability in the generalizability of the trials, ranging from 0.4% (VA I) to 33% (EWPHE). Only four trials were generalizable to more than 20% of the hypertensive population. Such poor generalizability appeared to be a function of the eligibility rather than of the exclusion criteria. Most people were not eligible because high levels of diastolic blood pressure that were required to be enrolled in the trials, as well as of age limits for inclusion in the trials. Overall, the proportion of people in our sample that would potentially have been enrolled in at least 1 trial was 57.5%, and 52.5% would potentially be enrolled in at least 2 trials.
Generalizability of the individual trials to the hypertensive population.
About 60% of hypertensive people requiring drug treatment according to the JNC VI had been told by a doctor that they had hypertension. Of these, 69% reported having a current prescription for anti-hypertensive drugs. Table compares the characteristics of people reporting a prescription for anti-hypertensive drugs vs. those not reporting a prescription for an antihypertensive medication. People in the first group were more likely to be elderly (42.3% treated vs. 16.4% not treated). Fifty-six percent of diagnosed hypertensives who were treated were women compared to 43.2% who were not treated. The distribution of race/ethnicity varied slightly according to treatment with a lower prevalence of whites among the treated group (81.5% vs. 85.5% not treated). Stroke, HF and renal failure were associated with more than a doubling of the probability of having a prescription for anti-hypertensive drugs. The prevalence of MI was 23% among those with prescription, and 15.5% among those without a prescription. Diabetes (28.8% vs. 25.9%) and chronic obstructive pulmonary disease (16.2% vs. 13.4%) were not associated with treatment. We observed a lower prevalence of people that would have been enrolled in at least two trials in the group receiving drug treatment. People similar to the population enrolled in clinical trials were 30% less likely to receive any hypertensive treatment, although the confidence intervals were wide (OR: 0.7, 95% CI: 0.4 – 1.3).
Comparison of the characteristics of people with diagnosed hypertension who were told to take antihypertensive medications vs. people not told.
After adjustment for demographic and clinical characteristics, the direction of the association between generalizability and treatment was reversed, with people similar to those included in clinical trial being 20% as likely to receive an antihypertensive medication than those without such characteristics (OR: 1.2; 95% CI: 0.6 – 2.8). The estimated association for the other variables was unchanged, except for physical impairment, which after the adjustment was associated with a decreased probability of being prescribed an antihypertensive drug.
Figure shows the rate of adherence to guidelines among the group to which the trials were generalizable compared to those to whom the trials were not generalizable. Adherence to guidelines was in general higher in the groups with target organ diseases or diabetes mellitus. In the group with high normal blood pressure and target organ disease, we found nobody that would have been included in at least two trials. In the other groups, generalizability had little effect on the adherence rate. People in the group to which the trials can be generalizable had a lower prevalence of treatment, although the differences were small. An exception was the group with stage 2/3 hypertension and at least 1 risk factor, in which people that would have been enrolled in at least two trials were more likely to be treated (81% vs. 75%).
Proportion of people receiving drug treatment according to trials' generalizability. Stratified by blood pressure and risk category as defined in table .
Of hypertensive people who had both a diagnosis and a prescription made by their physician, 76% were actually taking any medication at the time of the interview. Table shows the type of treatment reported. When we considered only drugs used in mono-therapy, we found that calcium channel blockers were the drugs most frequently used (15%), followed by diuretics and ACE-inhibitors (11%). β-blockers were taken as mono-therapy by 9% of persons. Considering any prescription, diuretics were the drugs most commonly used (41.5%), followed by calcium channel blockers (38.8%) and ACE-inhibitors (31.6%), and β-blockers (26.1%).
Use of anti-hypertensive drugs among people who had a medication prescribed by their doctors and that were taking the drug at the time of the interview.