An evidence-based medicine approach to economic studies: assessing the cost-effectiveness of competing strategies for colorectal cancer screening

Thiopurine-induced myelotoxicity in patients with inflammatory bowel disease: a review

AIM

Probably, the most important and potentially lethal adverse event of azathioprine (AZA) and mercaptopurine (MP) is myelosuppression. Our aim was to conduct a review of AZA/MP-induced myelotoxicity in inflammatory bowel disease (IBD) patients.

METHODS

Bibliographical searches were performed in MEDLINE/EMBASE. The studies evaluating thiopurine-induced myelotoxicity in patients with IBD were reviewed. The cumulative incidence and the incidence rate of AZA/MP-induced myelotoxicity were calculated by a meta-analysis.

RESULTS

In total, 66 studies (8,302 patients) were included. The cumulative incidence of AZA/MP-induced myelotoxicity was 7% (95% confidence interval [CI] 6-8%). The incidence rate (per patient and year of treatment) of the drug-induced myelotoxicity was 3% (95% CI 3-4%). The risk was roughly similar with AZA and with MP (7%vs 9%). The duration of AZA/MP treatment in patients with myelotoxicity ranged from 12 days to 27 yr. The cumulative incidence of infections among AZA/MP-induced myelotoxicity patients was 6.5%. The cumulative incidence of severe myelotoxicity was 1.1% (incidence rate 0.9%). Three deaths were reported due to myelotoxicity (cumulative incidence 0.06%, 95% CI 0.02-0.17%). The risk of death among patients who developed myelotoxicity was 0.94% (95% CI 0.32-2.70%).

CONCLUSION

The incidence rate of myelotoxicity in IBD patients receiving AZA/MP is approximately 3% per patient and year of treatment. Although bone marrow toxicity may develop at any time after starting the therapy, this happens more frequently during the first months. The incidence rate of severe myelotoxicity is less than 1% per patient and year of treatment, and the mortality risk is less than 0.1% (which means that the risk of death among IBD patients who develop myelotoxicity is approximately 1%).

Colorectal neoplasia screening with virtual colonoscopy: when, at what cost, and with what national impact?

BACKGROUND & AIMS

When optimized, virtual colonoscopy may be highly sensitive for colorectal neoplasia. We evaluated the effectiveness and cost-effectiveness of virtual colonoscopy screening (VC) vs. colonoscopy screening (COLO) and the potential impact at the national level.

METHODS

Using a Markov model, we estimated the clinical and economic consequences of VC and COLO from ages 50 to 80 years. Using census data, we made projections to the national level.

RESULTS

In the best case considered (95%, 94%, and 87% sensitivity for colorectal cancer [CRC], polyps > or =10 mm, and polyps <10 mm), VC was nearly as effective as COLO. However, if test costs were equal, total cost per person was 15% greater for VC than COLO, making COLO dominant. When test cost for VC was < or =60% of test cost for COLO, the small benefit of COLO vs. VC cost >200,000 US dollars/incremental life-year. The greater the likelihood of being referred for colonoscopy after VC, the greater the advantage of COLO. With 75% screening adherence in the United States, VC and COLO could decrease CRC incidence by 46%-54%, with COLO requiring 6.9 million colonoscopies/yr, and VC, 3.2 million colonoscopies/yr, plus 5.4 million virtual colonoscopies/yr with VC.

CONCLUSIONS

Even if screening test sensitivities were similar, COLO is likely to be preferred over VC unless virtual colonoscopy costs significantly less than colonoscopy. VC may be most appropriate in persons unlikely to need colonoscopy, such as those at low CRC risk. If VC were substituted for COLO, the demand on resources would shift from endoscopic to radiologic services, but would not diminish.

An evidence-based approach to studies in cirrhosis and portal hypertension: medical management of mild to moderate ascites

Previous articles in this series have examined the critical appraisal of isolated structured clinical questions using the framework of evidence-based medicine. When patients are identified with a disease-specific process, however, an integrated approach for addressing multiple questions is required. This article, the sixth in the evidence-based medicine series for this journal, integrates critical appraisal techniques to examine the decision-making process used when evaluating a patient with cirrhosis and new-onset mild to moderate ascites. In the following clinical scenario, an approach is described for determining prognosis after the development of ascites and whether salt restriction and oral diuretics are effective therapies. The format is similar to other evidence-based medicine articles published in the Journal of the American Medical Association. The evidence-based medicine concepts have been expanded from previous articles, and examples from the hepatology literature have been used.