Publications

Objective

To describe a framework for leveraging big data for research and quality improvement purposes and demonstrate implementation of the framework for design of the Department of Veterans Affairs (VA) Colonoscopy Collaborative.

Methods

We propose that research utilizing large-scale electronic health records (EHRs) can be approached in a 4 step framework: 1) Identify data sources required to answer research question; 2) Determine whether variables are available as structured or free-text data; 3) Utilize a rigorous approach to refine variables and assess data quality; 4) Create the analytic dataset and perform analyses. We describe implementation of the framework as part of the VA Colonoscopy Collaborative, which aims to leverage big data to 1) prospectively measure and report colonoscopy quality and 2) develop and validate a risk prediction model for colorectal cancer (CRC) and high-risk polyps.

Results

Examples of implementation of the 4 step framework are provided. To date, we have identified 2,337,171 Veterans who have undergone colonoscopy between 1999 and 2014. Median age was 62 years, and 4.6 percent (n = 106,860) were female. We estimated that 2.6 percent (n = 60,517) had CRC diagnosed at baseline. An additional 1 percent (n = 24,483) had a new ICD-9 code-based diagnosis of CRC on follow up.

Conclusion

We hope our framework may contribute to the dialogue on best practices to ensure high quality epidemiologic and quality improvement work. As a result of implementation of the framework, the VA Colonoscopy Collaborative holds great promise for 1) quantifying and providing novel understandings of colonoscopy outcomes, and 2) building a robust approach for nationwide VA colonoscopy quality reporting.

BACKGROUND & AIMS

The fecal immunochemical test (FIT) is widely used in colorectal cancer (CRC) screening. The OC-Light FIT is 1 of 2 FITs recommended for CRC screening by the Preventive Services Task Force guidelines. However, little is known about its ability to detect CRC in large average-risk populations.

METHODS

We performed a retrospective cohort study of patients (50-75 years old) in the San Francisco Health Network who were screened for CRC by OC-Light FIT from August 2010 through June 2015. Patients with a positive result were referred for colonoscopy. We used electronic health records to identify participants with positive FIT results, and collected results from subsequent colonoscopies and pathology analyses. The FIT positive rate was calculated by dividing the number of positive FIT results by the total number of FIT tests completed. The primary outcome was the positive rate from OC-Light FIT and yield of neoplasms at colonoscopy. Secondary outcomes were findings from first vs subsequent rounds of testing, and how these varied by sex and race.

RESULTS

We collected result from 35,318 FITs, performed on 20,886 patients; 2930 patients (8.3%) had a positive result, and 1558 patients completed the follow-up colonoscopy. A positive result from the FIT identified patients with CRC with a positive predictive value of 3.0%, and patients with advanced adenoma with a positive predictive value of 20.8%. The FIT positive rate was higher during the first round of testing (9.4%) compared to subsequent rounds (7.4%) (P < .01). The yield of CRC in patients with a positive result from the first round of the FIT was 3.7%, and decreased to 1.8% for subsequent rounds (P = .02).

CONCLUSIONS

In a retrospective analysis of patients in a diverse safety-net population who underwent OC-Light FIT for CRC screening, we found that approximately 3% of patients with a positive result from a FIT to have CRC and approximately 21% to have advanced adenoma.

Rosai-Dorfman disease (RDD) is a rare, nonmalignant disorder of histiocyte proliferation typically involving the cervical lymph nodes. However, a subset of patients with RDD will display extranodal manifestations that are highly variable in presentation, more challenging to diagnose, and less likely to spontaneously regress compared to nodal disease. While case reports of extranodal involvement in nearly every organ system exist, documented instances of mediastinal and pulmonary artery involvement are particularly rare. This study describes the case of a middle-aged woman presenting with new onset right heart failure who was found to have extranodal RDD in the form of a large mediastinal mass with invasion and occlusion of the main pulmonary arteries.