Faculty Peer Reviewed
Prevention is the best medicine
It is usually easier to prevent disease rather than to treat it once it has developed. Several journals this week set out to showcase various ways in which we can optimally prevent disease. While these recommendations go beyond regular disease screening, balanced diets, and exercise, they remind us that we, as health car providers, must continue to uncover new ways to prevent disease.
We begin with an examination of the optimal dose of aspirin used in the prevention of cardiovascular (CV) disease. The Annals of Internal Medicine published a post hoc observational analysis from a double-blinded, placebo-controlled, randomized trial of over 15,500 patients with either known CV disease or multiple risk factors. Steinhubl et al. used primary data from the CHARISMA (Clopidogrel for High Atherothrombotic Risk and Ischemic Stabilization, Management, and Avoidance) study, which randomly assigned high-risk individuals, who were also on ASA, to receive either plavix or placebo. Patients were excluded if they had a recent indication for treatment with plavix, namely recent MI or stent placement. After 6 months, the researchers studied the incidence of MI, stroke, and CV death. They did a post hoc analysis to examine the effects of ASA dose on efficacy and safety endpoints (severe life-threatening bleeding). They divided patients into a low dose ASA group (<100mg) and a high dose group (>100mg). They found that patients on plavix and high dose ASA had a higher incidence of CV death (5.2% vs. 3.4%, P=0.043) and stroke (3.6% vs. 2.4%, P=0.022), but not MI, as compared to the low dose ASA group. Additionally, they found that these patients also had a higher incidence of severe life-threatening bleeding (2.6% vs. 1.7%, P=0.04) as compared to the low dose ASA group. They concluded that high dose ASA (>100mg) was associated with no clear benefit and possibly increased risk. Therefore, we probably need not treat our at-risk patients with doses of ASA exceeding 100mg/day.
A study published in the New England Journal of Medicine this week examined the role of circumcision in the prevention of HSV-2, HPV, and syphilis. The study’s authors enrolled 5534 HIV-negative patients, of whom 3393 were also HSV-2 negative. 1684 of these patients were randomized to undergo immediate circumcision (intervention group), while those who remained uncircumcised served as controls. After 24 months follow-up, 7.8% on the intervention group and 10.3% of the control group had become positive for HSV-2 (adjusted hazard ratio in the intervention group 0.72, P= 0.008). The prevalence of high-risk HPV genotypes was 18% in the intervention group vs. 27.9% in the control group (adjusted risk ratio 0.65, P=0.009). There was no statistically significant difference between the two groups in infection by syphilis. The authors concluded that circumcision is not only important for the reduction of HIV infection, but also in the reduction of HSV-2 and HPV infection.
In JAMA this week, Timsit et al. evaluated the use of chlorhexidine-impregnated sponges and frequency of dressing changes in the prevention of catheter-related infections (CRI) in 1636 patients. They defined catheter-related infections as clinical sepsis with or without bloodstream infection, and they compared dressing changes at three vs. seven days. They found that in patients who were treated with chlorhexidine-impregnated sponges CRIs occurred in 0.6/1000 catheter days, whereas those who were treated with regular dressings developed CRIs in 1.4/1000 catheter days (P=0.03). They noted no increase in resistance of skin bacteria once the chlorhexidine sponges were removed. They calculated that the chlorhexidine sponges prevented 1 major CRI per 117 catheters placed. Additionally, catheter colonization occurred in 7.8% of catheters that were changed every three days and in 8.6% of catheters that were changed every seven days. This difference was not statistically significant. Thus, the authors concluded that the use of chlorhexidine-impregnated sponges can reduce the rate of CRI though changing the dressing more often than every seven days may not decrease rates of catheter colonization.
Finally, the NY Times reviewed two primary articles published in major journals. The first, published in Circulation last week, examined how rapidly the benefits of exercise after an MI disappear once patients cease exercising. Vona et al. showed measured flow-mediated dilation of arteries in patients who were asked to exercise and those who were asked to remain idle. They then evaluated all of the patients after being idle for 4 weeks. The benefits in blood flow, which were originally seen the exercise group all but disappeared after 4 weeks of exercise cessation. The second was published in the Archives of Internal Medicine and discussed the dose-dependent benefits of vitamin D supplements in the prevention of fractures. They found that only administration of vitamin D3 and not D2 were associated with a decreased risk of fracture. They report that patients need to take in more than 400U/day to see the benefits. Those who appropriately take vitamin D supplements can experience up to a 20% reduction in non-vertebral fractures and an 18% reduction in hip fractures. The fact that these 2 studies were showcased in the Times reaffirms the importance of uncovering new preventative measures and sharing them with the general public. In short, you need more than just an apple a day to keep the doctor away.
Reviewed by Michael Poles MD, Associate Editor, Clinical Correlations
Tobian AR, Serwadda D, Quinn TC, et al. Male Circumcision for the Prevention of HSV-2 and HPV Infections and Syphilis. NEJM. Mar 2009;360:1298-309.
Steinhubl SR, Bhatt DL, Brennan DM, et al. Aspirin to Prevent Cardiovascular Disease: The Association of Aspirin Dose and Clopidogrel With Thrombosis and Bleeding. Ann of Int Med. Mar 2009;150(6).
Timsit JF, Schwebel C, Bouadma L, et al. Chlorhexidine-Impregnated Sponges and Less Frequent Dressing Changes for Prevention of Catheter-Related Infections in Critically Ill Adults. JAMA. Mar 2009;301(12):1231-1241.
Vona M,, Codeluppi GM, Iannino T, et al. Effects of Different Types of Exercise Training Followed by Detraining on Endothelium-Dependent Dilation in Patients With Recent Myocardial Infarction. Circulation. Mar 2009; doi:10.1161/ CIRCULATIONAHA.108.821736.
Bischoff-Ferrari HA, Willett WC, Wong JB, et al. Prevention of Nonverterbral Fractures with Oral Vitamin D and Dose Dependency. A Meta-analysis of Randomized Controlled Trials. Arch Intern Med. Mar 2009;169(6):551-561.