In Wright et al.'s "Systematic Review of Antihypertensive therapies: Does the evidence assist in choosing a first-line drug?" the researchers review 38 different trials in order to determine if a first-line drug is identified in the realm of antihypertension drugs. According to the Critical Appraisal Skills Programme (CASP) appraisal tool, the researchers provide a valid study that can provide clear policy and practice change in the field of hypertension research and treatment.
The researchers, in their review, ask a clearly focused question - they wish to compare the effectiveness and efficacy from reputable trials in order to find first-line drugs for antihypertension therapies, using drug-drug comparison trials. The review includes the proper type of study, as a systemic review allows for a complete and comprehensive analysis of each of the trials at once, especially when comparing a first line drug (e.g. thiazide) to a placebo.
The researchers attempted to provide a significant number of relevant studies, though it is always possible that a higher sample size could have provided them with a clearer conclusion. Databases used were MEDLINE and the Cochrane Library, as well as previous meta-analyses. It appears as though the majority of the studies used took place in Western countries with English speaking researchers; however, the age and ethnicity of the participants in these studies vary from young to old, focusing on middle-aged to old men due to their higher prevalence for hypertension.
The researchers used very on-target and high quality studies in their systematic review. During their search, they took great care to exclude trials that used antihypertensive drugs for other indications, keeping their included studies relevant to their research question. Their inclusion criteria were also very strict, including first-line drug therapy comparisons, clearly defined first-line treatment and more. The results of each study are combined and organized by drugs used (Thiazide, beta blocker, CCB, et al.) and compared to each other to see how effective each drug was when comparing the results side by side. The results of the study are clearly displayed in several tables organized by drug and outcome, showing the relative risk ratio between active treatment and no treatment in their respective trials.
The researchers presented the results using a fixed-effects model and a relative risk ratio; they weighed each trial using the inverse of the within-study variance and a between-study variance component. They also calculated the risk difference, absolute risk reduction, and number needed to treat only for the number of total cardiovascular events found in each trial.
The researchers' results are fairly precise, given the 95% CI that is employed in this study of the trials. The researchers believe that the results can be applied to a local population, as the results seem fairly universal, and do not vary depending on setting. Furthermore, the authors believe that no noticeable change to the relative risk ratio would occur if certain studies were excised based on geography-based factors.
All important outcomes were considered by the researchers in this systemic review. The evidence being reviewed may potentially lead to policy or practice change in the field of hypertension therapy. With the results of this study, thiazide is presented as a fully adequate first-line drug to use in these trials, due to the reduced risk of death, stroke and coronary artery disease the authors saw in their findings.
References
Wright, J.M., Lee, C.H., & Chambers, G.K. (1999). Systematic review of antihypertensive
therapies: Does the evidence assist in choosing a first-line drug? Canadian Medical
Association Journal 161 (1): 25.
