A validated algorithm to ascertain colorectal cancer recurrence using registry resources in Denmark

Abstract

Colorectal cancer recurrences are difficult to ascertain accurately and efficiently. We developed and validated an algorithm to identify recurrences that uses Danish medical registries. The algorithm uses metastasis and chemotherapy codes in the Danish National Patient Registry and codes indicating cancer recurrence in the Danish Pathology Registry. We applied the algorithm to a cohort (n 5 21,246) of colorectal cancer patients diagnosed 2001-2011 and followed through 2012. In a cohort (n 5 355) of two groups of actively followed patients, we compared the imputed recurrence data with recurrences diagnosed by regular follow-up. We compared cumulative incidence curves of imputed recurrence in local and regional stage patients from the large cohort, and of imputed and diagnosed recurrences in the actively followed cohort. In the 355 members of the actively followed cohort, our algorithm correctly identified 60 of 63 recurrences [sensitivity 5 95%; 95% confidence interval (CI) 87-99%] and misclassified only 10 of 292 without recurrence (specificity 5 97%; 95% CI 94-98%). Cumulative incidence curves showed that members of the large cohort with regional disease had much higher incidence of imputed recurrence than those with local disease. In the actively followed cohort, the cumulative incidence of recurrence overlapped substantially when recurrence was imputed by our algorithm or using the follow-up data. Despite some limitations regarding ambiguous pathology codes, our algorithm showed excellent performance against actively followed recurrence data, and the expected relation between recurrence risk and cancer stage. It can be used in the Danish registries and adapted to similar registries elsewhere.

Association between metformin use after surgery for colorectal cancer and oncological outcomes: A nationwide register‐based study

“…Recurrence during follow‐up was estimated using a validated algorithm described in detail elsewhere . In brief, at least one of the following criteria must be met: NPR‐registered metastases code 180 days after the first colorectal cancer surgery, and without a new primary cancer diagnosis between the date of colorectal cancer surgery and date of metastases code. NPR‐registered cytostatic therapy codes 180 or more days after the first colorectal cancer surgery and 60 or more days after the last cytostatic therapy code, and without a new primary tumor in the time period between colorectal cancer surgery and date of cytostatic therapy code. DPR‐registered SNOMED combinations indicating recurrence recorded 180 or more days after the first colorectal cancer surgery, and without a new primary cancer diagnosis. A code specific for local colorectal cancer recurrence in the NPR any time after primary diagnosis: DC189X and DC209X.…”

Time from incident primary cancer until recurrence or second primary cancer: Risk factors and impact in general practice

“…The sensitivity of the algorithms ranged from 85% to 95%, and the specificity ranged from 93% to 99% (Lash et al, 2015;.…”

“…Hence, patients with CR were identified by validated algorithms based on Danish national health registers (Erichsen et al, 2010;Gjerstorff, 2011;Ingeholm, Gögenür, & Iversen, 2016;Schmidt et al, 2015). These algorithms have been described in detail elsewhere (Lash et al, 2015;Rasmussen, Jensen, Virgilsen, Jensen, & Vedsted, 2018;Rasmussen et al, 2019). The algorithms identified patients registered with procedure codes in the Danish National Patient Register (DNPR; Schmidt et al, 2015) corresponding to curative cancer treatment regimens (Figure 1), that is primary cancer surgery and either surgery or radiotherapy corresponding to curative treatment (≥15 fractions) for bladder cancer.…”

“…No routine registration of remission and CR is available outside clinical trials, and research in CR is generally limited to small and selected study populations (Warren & Yabroff, 2015). We used recently validated register-based algorithms to identify patients with CR (Lash et al, 2015;, which enabled us to conduct this study. The Danish national registers have high completeness and accuracy (Erichsen et al, 2010;Gjerstorff, 2011;Schmidt, Pedersen, & Sørensen, 2014;Schmidt et al, 2015), and the use of a personal identification number to link medical and socio-economic data at the personal level is a unique opportunity in population-based research (Thygesen, Daasnes, Thaulow, & Brønnum-Hansen, 2011).…”

Validating registry data on statins prescriptions by blood measurements

“…To confirm the colorectal cancer diagnosis and to obtain additional covariate information, we included only patients from the cohorts (n = 355) that were registered in the database of the Danish Colorectal Cancer Group. 20 Beginning in 2001, the database has registered all patients with an incident colorectal adenocarcinoma diagnosed or treated in surgical departments in Denmark. Completeness of colorectal cancer registration ranged from 98% to 100% during the 2001 to 2010 period.…”