2012- September R3 Journal Review
Tonelli M, Muntner P, Lloyd A, Manns BJ, et al. Risk of coronary events in people with chronic kidney disease compared with those with diabetes: a population-level cohort study. Lancet 2012; 380: 807-14. This population-based cohort study in Canada evaluated whether or not chronic kidney disease should be regarded as a coronary heart disease risk equivalent, just as diabetes already is. For participants, they screened a national database for routine laboratory studies for a creatinine equivalent of CKD stage III and IV and also if they had diabetes (using HgbA1c measurements). Then they followed up participants from the index lab date until the study end to see if they were admitted to the hospital for myocardial infarction and then, also, their short-term and long-term mortality. They had 1.2 million participants total for all the groups. They found that when the rate of MI in those with CKD (either w/ or w/o diabetes) was compared with diabetes (w/o CKD), the rate of myocardial infarction was significantly higher in those with CKD (p<0.0001). However, they also adjusted the results for age, socioeconomic status, and comorbidity, the rate of MI was lower in people with CKD than in those with diabetes, suggesting that some of the risk associated with CKD is also attributable to old age. Because of their results, the authors recommended adding CKD (eGFR<45 and proteinuria) as a coronary heart disease risk equivalent. Also because those with diabetes are already thought to be in the highest risk category for CAD, the addition of CKD to the criteria should only affect those without diabetes.
Santillanes G, et al. Prospective evaluation of a clinical practice guideline for diagnosis of appendicitis in children. Academic Emergency Medicine 2012; 19(8): 886-893. This was a prospective cohort study meant to evaluate the efficacy of a clinical practice guideline for imaging and surgical consultation in pediatric patients presenting with possible appendicitis. The guideline was developed by a group of radiologists, surgeons, and EM physicians. It divided patients into low, medium and high risk groups based on physical exam findings and the results of a CBC. Characteristics which were considered to increase risk included WBC count >10,000, PMN >67%, Bandemia, and RLQ tenderness. Based on their algorithm low risk patients were discharged with 6-12 hour follow-up. Ultrasound was the initial imaging modality of choice for medium risk patients, followed by CT if necessary. High risk patients had a surgical consult with imaging guided by their recommendations. The primary end-point was a diagnosis of appendicitis. Secondary end-points were CT use and negative appendectomy.
A total of 704 patients presented with inclusion criteria and of these 475 were enrolled. 31 were classified as low risk, 267 medium risk, and 177 high risk. Rates of appendicitis were 0% in the low risk group, 19% in the medium risk group, and 83% in the high risk group. There were 2 negative appendectomies, one from each of the medium and high risk groups. 4 patients had a missed diagnosis. One was not enrolled in the protocol initially but was found to be high risk on his return visit. The other 3 were classified as high risk on their initial visit and all had imaging performed. 2 of these violated study protocol by not having surgical consultation performed, however both had negative CT scans and ultrasounds but were admitted after their scheduled next day follow up. CT scans were performed on 199 patients, ultrasound on 299, and both on 155. 132 patients had not imaging performed. 61 patients were taken to the OR without imaging. CT scan had a Sensitivity of 91% and a specificity of 98%.
The clinical practice guideline presented in this study performed well. There are limitations, as it was evaluated at a single site and would require the cooperation of the surgical service. The interesting part of this study was the relatively low sensitivity of CT. Ultrasound was shown to have utility for diagnosis of appendicitis but not to rule it out. The multi-disciplinary approach utilized in this clinical practice guideline creates a model which should be studied in other centers and possibly implemented as a means of limiting radiation exposure, particularly to young children.