Effect of Aspirin on Vascular and Nonvascular Outcomes Meta-analysis of Randomized Controlled Trials

English: Schematic diagram of a plasma CVD (Ch...Image via WikipediaEffect of Aspirin on Vascular and Nonvascular Outcomes

Meta-analysis of Randomized Controlled Trials
Sreenivasa Rao Kondapally Seshasai, MD, MPhil; Shanelle Wijesuriya, MA, MBBChir; Rupa Sivakumaran, MA, MBBChir; Sarah Nethercott, MA, MBBChir;Sebhat Erqou, MD, PhD; Naveed Sattar, MD, PhD; Kausik K. Ray, MD 
Arch Intern Med. Published online January 9, 2012. doi:10.1001/archinternmed.2011.628
Background  The net benefit of aspirin in prevention of CVD and nonvascular events remains unclear. Our objective was to assess the impact (and safety) of aspirin on vascular and nonvascular outcomes in primary prevention.
Data Sources  MEDLINE, Cochrane Library of Clinical Trials (up to June 2011) and unpublished trial data from investigators.
Study Selection  Nine randomized placebo-controlled trials with at least 1000 participants each, reporting on cardiovascular disease (CVD), nonvascular outcomes, or death were included.
Data Extraction  Three authors abstracted data. Study-specific odds ratios (ORs) were combined using random-effects meta-analysis. Risks vs benefits were evaluated by comparing CVD risk reductions with increases in bleeding.
Results  During a mean (SD) follow-up of 6.0 (2.1) years involving over 100 000 participants, aspirin treatment reduced total CVD events by 10% (OR, 0.90; 95% CI, 0.85-0.96; number needed to treat, 120), driven primarily by reduction in nonfatal MI (OR, 0.80; 95% CI, 0.67-0.96; number needed to treat, 162). There was no significant reduction in CVD death (OR, 0.99; 95% CI, 0.85-1.15) or cancer mortality (OR, 0.93; 95% CI, 0.84-1.03), and there was increased risk of nontrivial bleeding events (OR, 1.31; 95% CI, 1.14-1.50; number needed to harm, 73). Significant heterogeneity was observed for coronary heart disease and bleeding outcomes, which could not be accounted for by major demographic or participant characteristics.
Conclusions  Despite important reductions in nonfatal MI, aspirin prophylaxis in people without prior CVD does not lead to reductions in either cardiovascular death or cancer mortality. Because the benefits are further offset by clinically important bleeding events, routine use of aspirin for primary prevention is not warranted and treatment decisions need to be considered on a case-by-case basis.

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Most women with screen-detected breast cancer have not had their life saved by screening

Age-standardised death rates from Breast cance...Image via Wikipedia

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That’s the conclusion of an article published today in the Archives of Internal Medicine. I’m on the run today, but here’s the abstract

Background Perhaps the most persuasive messages promoting screening mammography come from women who argue that the test “saved my life.” Because other possibilities exist, we sought to determine how often lives were actually saved by mammography screening.

Methods We created a simple method to estimate the probability that a woman with screen-detected breast cancer has had her life saved because of screening. We used DevCan, the National Cancer Institute‘s software for analyzing Surveillance Epidemiology and End Results (SEER) data, to estimate the 10-year risk of diagnosis and the 20-year risk of death–a time horizon long enough to capture the downstream benefits of screening. Using a range of estimates on the ability of screening mammography to reduce breast cancer mortality (relative risk reduction [RRR], 5%-25%), we estimated the risk of dying from breast cancer in the presence and absence of mammography in women of various ages (ages 40, 50, 60, and 70 years).
Results We found that for a 50-year-old woman, the estimated risk of having a screen-detected breast cancer in the next 10 years is 1910 per 100 000. Her observed 20-year risk of breast cancer death is 990 per 100 000. Assuming that mammography has already reduced this risk by 20%, the risk of death in the absence of screening would be 1240 per 100 000, which suggests that the mortality benefit accrued to 250 per 100 000. Thus, the probability that a woman with screen-detected breast cancer avoids a breast cancer death because of mammography is 13% (250/1910). This number falls to 3% if screening mammography reduces breast cancer mortality by 5%. Similar analyses of women of different ages all yield probability estimates below 25%.
Conclusions Most women with screen-detected breast cancer have not had their life saved by screening. They are instead either diagnosed early (with no effect on their mortality) or overdiagnosed.