Israel Medical Association Journal

In this review, the authors re-examine the role of aspirin in the primary prevention of cardiovascular disease. They discuss the history of the use of aspirin in primary prevention, the current guidelines, and the recent evidence surrounding aspirin use as primary prevention in special populations such as those with moderate cardiovascular risk, diabetes mellitus, and the elderly

Objectives: To examine the effect of meloxicam, a selective COX-2 inhibitor, or low dose aspirin on the development of experimental atherosclerosis in apoE knockout (KO) compared to wild-type (WT) mice. We aimed to test the hypothesis that meloxicam, a potential vasculitis inducer, would exacerbate atherosclerotic lesions while aspirin, which is known to reduce the incidence of thrombosis occlusive events, would increase protection in this model.

Methods: We randomly divided 36 male apoE KO and 36 WT mice, 8 weeks old. Mice were treated for 10 weeks with 0.1 mg/ml aspirin, or 0.05 mg/ml meloxicam, dissolved in their drinking water. Control groups received regular drinking water. At sacrifice, the hearts were removed for histochemical staining and plaque size and composition were examined.

Results: Aspirin-treated animals displayed a decreased atherosclerotic lesion area compared to the untreated control mice, while meloxicam had a null effect on the extent of atherosclerosis in Apo E KO mice.

Conclusions: These results suggest that low dose aspirin reduces early atherosclerosis, while inhibition of COX-2 by meloxicam is not associated with an increase in atherosclerotic plaque size in this mouse model.

Background: The effect of anti-platelet drugs on surgical blood loss and perioperative complications has not been studied in depth and the management of surgical patients taking anti-platelet medications is controversial.

Objective: To assess the effect of anti-platelet therapy on perioperative blood loss in patients undergoing appendectomy either laparoscopically or via open surgery.

Methods: We reviewed the files of all patients > 40 years old who underwent open or laparoscopic appendectomies from 2007 to 2010. Excluded were patients with short hospitalization and no follow-up of hemoglobin level, patients on warfarin treatment and patients who underwent additional procedures. Estimation of blood loss was based on decrease in hemoglobin level from admission to discharge. Risk factors for blood loss, such as anti-platelet therapy, age, gender, surgical approach, surgical time, surgical findings and complications, were analyzed.

Results: The final cohort included 179 patients (mean age 61 ± 14 years, range 40–93) of whom 65 were males. The mean perioperative hemoglobin decrease was 1.59 ± 1.07 mg/dl (range 0–5 mg/dl). Thirty-nine patients received anti-platelet therapy prior to surgery and 140 did not. No significant differences in decrease of hemoglobin level were found between patients receiving anti-platelet therapy and those who were not (1.73 ± 1.21 vs. 1.55 ± 1.02 mg/dl, P = 0.3). In addition, no difference was found between patients on anti-platelet therapy operated laparoscopically and those operated in an open fashion (1.59 ± 1.18 vs. 2.04 ± 1.28 mg/dl, P = 0.29). Five patients required blood transfusions, two of whom were on anti-platelet therapy. Blood loss was significantly greater in patients with a perforated appendicitis and in those with an operative time of more than one hour.

Conclusions: Anti-platelet therapy does not pose a risk for increased blood loss following emergent appendectomy performed either laparoscopically or in an open fashion.
 

Objective: To examine the effect of aspirin administration (low dosage) on the susceptibility of LDL to oxidative modification healthy volunteers.

Methods: Aspirin 75 mg was administered daily for 2 weeks to 10 healthy volunteers selected from the medical staff and students at the faculty of medicine. The main outcome measure was ex vivo oxidation of LDL by ultraviolet C irradiation or by peroxyl free redicals generated by AAPH (2,2’ -azobis 2-amidinopropane hydrochloride). The extent of LDL oxidation was determined by measuring the formed amounts of thiobarbituric-acid reactive substances, lipid peroxides and conjugated dienes.

Results: Following exposure to UV_C irradiation there was a significant (p<0.01) increase (10.8%) in TBARS concentrations and a significant (p≤0.05) increase (5.4%) in PD concentrations in LDL withdrawn after aspirin treatment as compared to LDL withdrawn before aspirin treatment. Following incubation with AAPH there was a significant (p<0.05) increase (15%) in PD concentrations and a significant (p<0.05) reduction (10%) of the LDL oxidation lag time in LDL withdrawn after aspirin intake as compared to LDL withdrawn before aspirin treatment.

Conclusions: Aspirin treatment given to healthy volunteers at a dose of 75 mg/day increased the susceptibility of their plasma LDL to oxidative modification ex vivo. Our study provides, for the first time, in vivo evidence of pro-oxidative properties of aspirin already suggested by previous in vitro trials.

Background: The management of aspirin therapy before an invasive procedure poses a frequent clinical dilemma due to uncertainty regarding b[AS1] leeding versus thromboembolic risks associated with continuation or withdrawal of the drug. There is no evidence-based data to refer to.

Objectives: To assess the opinions of internal medicine physicians regarding aspirin therapy prior to an invasive procedure.

Methods: A questionnaire presenting nine hypothetical cases with different combinations of bleeding and thromboembolic risk was given to physicians in an Internal Medicine Division during a personal interview. For each case the participants had to choose between withdrawal of aspirin prior to an invasive procedure, continuation of aspirin, or substitution of low molecular weight heparin for aspirin. Results: Sixty-one physicians participated in the survey. For a patient with low thromboembolic risk, 77% (95% confidence interval 65.3–86.3%), 95% (87.2–98.7%) and 97% (89.6–99.5%) of physicians elected to discontinue aspirin prior to a low, intermediate or high bleeding risk procedure, respectively. For intermediate risk patients, 23% (95% CI[1] 13.7–34.7%), 59% (46.4–70.8%) and 74% (61.7–83.6%) would discontinue aspirin prior to a low, intermediate or high risk procedure, and 5% (95% CI 1.3–12.8%), 23% (13.7–34.7%) and 18% (9.9–29.2%) would substitute LMWH[2] for aspirin. For a patient with high thromboembolic risk, 1.6% (95% CI 0.08–7.8%), 11.5% (5.2–21.4%) and 18% (9.9–29.2%) recommended discontinuing aspirin prior to a low, intermediate or high risk procedure, respectively. In these situations, 18% (95% CI 9.9–29.2%), 53% (40.0–64.7%) and 57% (44.8–69.3%), respectively, would substitute LMWH for aspirin.

Conclusions: The results of the current investigation may help practicing physicians to decide whether to discontinue aspirin therapy prior to invasive procedures. The possible use of LMWH to replace aspirin as suggested here should be further evaluated in a controlled clinical study.

 

Objectives: To investigate the mechanisms of these effects.

Methods: The study group included 106 long-term care stable geriatric inpatients. Diet and drugs were kept stable. The study lasted 5 weeks; during the first 2 weeks 100 mg aspirin was administered once a day. Clinical and laboratory follow-up were performed at baseline and weekly for the next 3 weeks. The glomerular filtration rate was estimated by creatinine clearance measured in 24 hour urine and serum creatinine, and by the Cockcroft-Gault formula (C-G) equation. Uric acid clearance (Cu acid) was determined from serum concentrations and 24 hour excretion of uric acid. Patients with serum creatinine > 1.5 mg/dl were not included.

Results: After 2 weeks on low dose aspirin, measured creatinine and uric acid clearances decreased significantly compared with the initial values in 70% and 62% of the patients, respectively, with mean decreases of 19% and 17%, respectively (P < 0.001). Blood urea nitrogen increased by 17% while serum creatinine and uric acid concentrations increased by 4% (P < 0.05 for all). The C-G[1] values decreased by 3% (P < 0.05). After withdrawal of aspirin all parameters improved. However, 67% of the patients remained with some impairment in their measured Ccr[2], compared to baseline. Patients who reacted adversely to low dose aspirin had significantly better pre-study renal function (Ccr), lower hemoglobin and lower levels of serum albumin.

Conclusions: Short-term low dose aspirin affected renal tubular creatinine and uric acid transport in the elderly, which may result in a prolonged or permanent deterioration of the renal function. It is suggested that renal functions be monitored even with the use of low dose aspirin in elderly patients.

There is increasing evidence to suggest that aspirin and other non-steroidal anti-inflammatory drugs reduce the risk of colorectal cancer. This observation is supported by animal studies that show fewer tumors per animal and fewer animals with tumors after administration of several different NSAIDs. Intervention data in familial adenomatous polyposis have established that the effect is exerted on the process of human colonic adenoma formation. Supportive evidence in sporadic colorectal neoplasia, derived from 22 of 24 studies (both case-control and cohort), found a reduced risk in men and women for cancers of the colon and the rectum and for both aspirin and the other NSAIDs. Earlier detection of lesions as a result of drug-induced bleeding does not seem to account for these findings. Although the molecular mechanism responsible for the chemopreventive action of this class of drugs is not yet completely understood, the protection may affect several pathways including both cell cycle arrest and induction of apoptosis.

In the third millennium the question is not if but how. Based on the consistency of epidemiological, clinical and experimental data, the association between regular long-term aspirin or NSAIDs intake and a decreased death rate from colorectal cancer is sound and there is no need for further placebo trials. At the same time, despite this consistency there is no clear data on the dose, duration or frequency of use for cancer-preventive activity.