QUALITY-ADJUSTED METAANALYSIS OF THE HYPERTENSION CORONARY DILEMMA/

Primary investigators of randomized drug trials in hypertension were i nvited to rate quality of such trials. The intention of the survey was to ask if antihypertensive drug therapy reduces incidence of coronary heart disease (CHD) in hypertensive patients. Response was obtained f or 7 of the 11 invited investigators, covering 69% of patients and 75% of CHD cases. Principal component analysis was used to construct a qu ality score based on answers to 12 questions along visual analog scale s. The score correlated well with the answer to a global question of o verall quality given by the raters. No systematic tendency toward favo ring one's own trial could be demonstrated, therefore, all raters have contributed to the rating. The trials with the highest rated quality to answer the research question were Systolic Hypertension in the Elde rly Program (SHEP), Australian National Blood Pressure Study, Medical Research Council, Veterans Administration, and European Working Party of Hypertension in the Elderly. The large Heart Detection and Follow-u p Program (HDFP) trial was rated at 11th place among the trials with a score of <40% of the SHEP. The small trials performed in the 1960s we re placed at the bottom of the ranking list. Because SHEP is the only trial without diastolic hypertension, results were given with and with out SHEP results. When incorporating the quality score into a meta-ana lysis of CHD outcome, results were dependent on whether SHEP was inclu ded or not. For diastolic hypertension only, the effect of therapy was estimated to be about 8% for all higher quality studies, whereas incl usion of the lower quality HDFP changed it to 14%. When isolated systo lic hypertension trial was pooled with the others, no major relation t o quality rating was observed. A 14% CHD preventive efficacy was estab lished when pooling the three top quality studies. This stayed unchang ed until HDFP at rank 11 was included raising this estimate to 16%. In clusion of the two latest published trials in the elderly, the Medical Research Council trial of treatment of hypertension in older adults a nd the Swedish Trial in Old Patients with hypertension, did not change this overall estimate of 16% (standard error = 3.8%). It is concluded that if all randomized drug trials in hypertension had the same treat ment efficacy, the estimated CHD prevention would be in the range of 1 5%. Subgroup analyses revealed no relationship to age, but a differenc e in efficacy was shown depending on whether the trials were performed in the United States or elsewhere. Also, patients at higher risk leve ls showed better benefit than lower risk patients.