A Validated Register-Based Algorithm to Identify Patients Diagnosed with Recurrence of Surgically Treated Stage I Lung Cancer in Denmark

Linda Aagaard Rasmussen; Niels Lyhne Christensen; Anne Winther-Larsen; Susanne Oksbjerg Dalton; Line Flytkjær Virgilsen; Henry Jensen; Peter Vedsted

doi:10.2147/CLEP.S396738

A Validated Register-Based Algorithm to Identify Patients Diagnosed with Recurrence of Surgically Treated Stage I Lung Cancer in Denmark

Clin Epidemiol. 2023 Mar 1:15:251-261. doi: 10.2147/CLEP.S396738. eCollection 2023.

Authors

Linda Aagaard Rasmussen¹, Niels Lyhne Christensen², Anne Winther-Larsen³, Susanne Oksbjerg Dalton^{4

5}, Line Flytkjær Virgilsen¹, Henry Jensen¹, Peter Vedsted¹

Affiliations

¹ Research Unit for General Practice, Aarhus, Denmark.
² Department of Pulmonary Medicine and Allergy, Aarhus University Hospital, Aarhus, Denmark.
³ Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.
⁴ Survivorship and Inequality in Cancer, Danish Cancer Society Research Center, Copenhagen, Denmark.
⁵ Department of Clinical Oncology & Palliative Care, Zealand University Hospital, Næstved, Denmark.

Abstract

Introduction: Recurrence of cancer is not routinely registered in Danish national health registers. This study aimed to develop and validate a register-based algorithm to identify patients diagnosed with recurrent lung cancer and to estimate the accuracy of the identified diagnosis date.

Material and methods: Patients with early-stage lung cancer treated with surgery were included in the study. Recurrence indicators were diagnosis and procedure codes recorded in the Danish National Patient Register and pathology results recorded in the Danish National Pathology Register. Information from CT scans and medical records served as the gold standard to assess the accuracy of the algorithm.

Results: The final population consisted of 217 patients; 72 (33%) had recurrence according to the gold standard. The median follow-up time since primary lung cancer diagnosis was 29 months (interquartile interval: 18-46). The algorithm for identifying a recurrence reached a sensitivity of 83.3% (95% CI: 72.7-91.1), a specificity of 93.8% (95% CI: 88.5-97.1), and a positive predictive value of 87.0% (95% CI: 76.7-93.9). The algorithm identified 70% of the recurrences within 60 days of the recurrence date registered by the gold standard method. The positive predictive value of the algorithm decreased to 70% when the algorithm was simulated in a population with a recurrence rate of 15%.

Conclusion: The proposed algorithm demonstrated good performance in a population with 33% recurrences over a median of 29 months. It can be used to identify patients diagnosed with recurrent lung cancer, and it may be a valuable tool for future research in this field. However, a lower positive predictive value is seen when applying the algorithm in populations with low recurrence rates.

Keywords: Denmark; algorithms; lung neoplasms; recurrence; registries; validation study.

Grants and funding

The study was supported by the Research Foundation for General Practice in the Central Denmark Region. The funder was not involved in any aspects of the study.