Table 2 Data extraction of the meta-analysis
Khan et al. 2006. Re-examining the efficacy of β–blockers for the treatment of hypertension: a meta-analysis, CMAJ, 174(12): 1737-42 [33] | ||
Country | Canada | |
Funding | Not stated | |
Setting | Not stated | |
Objective | To explore the efficacy (stroke, myocardial infarction and death) of beta blockers in different age groups | |
Inclusion and exclusion criteria | ||
Population | Hypertension, distinguish between “younger” patients <60 years (mean age ranged from 45.5 to 56.2 years, n=10 trials and n=50,612 patients) and “older” patients ≥60 years (60.4 to 76 years, n=11 trials and n=95,199 patients, 9 trials out of 11 with mean age ≥65 years). | |
Intervention | Beta blocker as first-line therapy for hypertension in preventing major cardiovascular events | |
Control | No treatment, placebo, diuretic, ACE inhibitor, calcium-channel blocker, angiotensin-receptor blocker | |
Outcomes | Stroke, myocardial infarction, or death | |
Study designs | Randomized controlled trials | |
Methods | ||
Study design | Systematic review including meta-analysis. Results of the individual studies are combined to produce an overall statistic. | |
Last date searched | 18 January 2006 | |
Data bases searched | PubMed (1950-18.01.2006) | |
Other sources searched | Hand search, reference lists of published hypertension meta-analysis (MEDLINE) and the Cochrane Library. Contacted Canadian hypertension experts. | |
Number of included studies | 21 Randomized controlled trials | |
Number of included patients | 145,811 | |
Outcomes, results | ||
Primary | ||
Composite cardiovascular outcome of death, nonfatal myocardial infarction or nonfatal stroke | Beta blockers reduced event rates compared with placebo (RR 0.86, 95% CI 0.74–0.99, based on 794 events in 19,414 patients), in trials enrolling younger patients, but benefits were not found in trials enrolling older patients (RR 0.89, 95% CI 0.75–1.05, based on 1115 events in 8,019 patients). Among 30,412 patients younger than 60 years of age, there was no difference in event rates between those randomly assigned to beta blockers therapy compared with those receiving other antihypertensive agents (1515 events, RR 0.97, 95% CI 0.88–1.07). However, in the 79,775 patients 60 years of age or older, beta blockers were associated with a higher risk of events than other antihypertensive agents (7405 events, RR 1.06, 95% CI 1.01–1.10). | |
Secondary | ||
Beta blocker compared to placebo | “Younger population” < 60 years | “Older population” ≥ 60 years |
Death | RR 0.94, 95% CI 0.79–1.10 | RR 0.91, 95% CI 0.74–1.12 |
Nonfatal myocardial infarction | RR 0.85, 95% CI 0.71–1.03 | RR 0.98, 95% CI 0.83–1.16 |
Nonfatal stroke | RR 0.84, 95% CI 0.65–1.10 | RR 0.78, 95% CI 0.63–0.98 |
Heart failure | RR 1.05, 95% CI 0.72–1.54 | RR 0.54, 95% CI 0.37–0.81 |
Beta blocker compared to other antihypertensive agents | “Younger population” < 60 years | “Older population” ≥ 60 years |
Death | RR 0.97, 95% CI 0.83–1.14 | RR 1.05, 95% CI 0.99–1.11 |
Nonfatal myocardial infarction | RR 0.97, 95% CI 0.86–1.10 | RR 1.06, 95% CI 0.94–1.20 |
Nonfatal stroke | RR 0.99, 95% CI 0.67–1.44 | RR 1.18, 95% CI 1.07–1.30 |
Heart failure | RR 0.93, 95% CI 0.64–1.34 | RR 0.98, 95% CI 0.87–1.11 |
Subgroup analysis, ≥60 years | ||
Beta blocker compared to placebo or no treatment (5 trials and n=8,019 patients, range mean age 65 to 75.7 years) | ||
Composite cardiovascular outcome of death, nonfatal myocardial infarction or nonfatal stroke | Beta-blockers´ benefits were not found in trials enrolling older patients RR 0.89, 95% CI 0.75–1.05, based on 1,115 events in 8,019 patients. | |
Death | RR 0.98, 95% CI 0.83–1.16 | |
Nonfatal myocardial infarction | RR 0.98, 95% CI 0.83–1.16 | |
Nonfatal stroke | RR 0.78, 95% CI 0.63–0.98 | |
Heart failure | RR 0.54, 95% CI 0.37–0.81 | |
Beta blocker compared to other antihypertensive agents (7 trials and n=87,180 patients, range mean age 60.4 to 76 years) | ||
Composite cardiovascular outcome of death, nonfatal myocardial infarction or nonfatal stroke | Beta blockers were associated with a higher risk of events than were other antihypertensive agents (7,405 events, RR 1.06, 95% CI 1.01–1.10). | |
Death | RR 1.05, 95% CI 0.99–1.11 | |
Nonfatal myocardial infarction | RR 1.06, 95% CI 0.94–1.20 | |
Nonfatal stroke | RR 1.18, 95% CI 1.07–1.30 | |
Heart failure | RR 0.98, 95% CI 0.87–1.11 | |
Conclusion | ||
Beta blockers should not be considered first-line therapy for older hypertensive patients without another indication for these agents; however, in younger patients beta blockers are associated with a significant reduction in cardiovascular morbidity and mortality. | ||
Quality appraisal | ||
Quality criteria for systematic reviews and meta-analyses | Author´s judgement | Support for judgement |
Precise and accurately defined research question (e.g. PICO) | Yes | Criteria for considering studies are explicitly explained in the paper. The PICOS scheme can be applied |
Well-defined selection criteria | Yes | See above |
Was an ‘a priori’ design provided? | No | There is no published protocol for this meta-analysis |
Systematic literature research | Yes | Search method is illustrated |
Appropriate search strings, data bases and hand search | No | Only a PubMed search and a hand search were conducted. A very limited search string was used. |
At least two reviewers for selecting retrieved studies | Unclear | The review process, screening abstracts and reading full texts is not described. Two authors extracted outcome data from each trial independently. The inter observer kappa for trial inclusion was 0.94 |
Well documented process of selection of included studies (e.g. PRISMA flow diagram) | Unclear | Some kind of PRISMA flow was used, but the review process is unclear. A list of excluded studies is missing. |
Quality of the studies documented and considered for the synthesis of evidence | No | Quality appraisal of studies is lacking |
Was the conflict of interest stated? | Yes | None declared. |
Assessed publication bias | No | Publication bias not assessed |
Heterogeneity statistically analysed | Yes | X2 tests were used to test heterogeneity |
Quality of internal validity | Poor | No study quality assessment was performed |