JMIR Publications

ABSTRACT

Background:

Starting in 2010, the Epidermal Growth Factor Receptor (EGFR) kinase inhibitors, erlotinib and gefitinib, were introduced into routine use in Aotearoa New Zealand (NZ) for treating advanced lung cancer, but their impact in that setting is unknown.

Objective:

To understand the effectiveness and safety of these new personalised lung cancer treatments, and contributions made by concomitant medicines and other factors to adverse outcomes, in the general NZ patient population. The study protocol and results of a validation sub-study are presented.

Methods:

This retrospective cohort study will include all NZ patients with advanced EGFR mutation-positive lung cancer, who were first dispensed erlotinib or gefitinib before 30 September 2020 and followed until death or for at least one year. Routinely collected health administrative and clinical data will be collated from national electronic cancer registration, hospital discharge, mortality registration and pharmaceutical dispensing databases, by deterministic data linkage using National Health Index numbers. The primary effectiveness and safety outcomes will be time-to-treatment discontinuation and serious adverse events, respectively. The primary variable will be high-risk concomitant medicines use with erlotinib or gefitinib. A validation sub-study was undertaken of national electronic health databases as the data source, and of methods for determining patient eligibility and identifying study outcomes and variables.

Results:

National electronic health databases and clinical records agreed in determining patient eligibility and for identifying serious adverse events, high-risk concomitant medicines use and other categorical data, with overall agreement and Kappa statistics of >90% and >0.8, respectively. Dates for estimating time-to-treatment discontinuation and other numerical data, showed small differences, mostly with nonsignificant P values and confidence intervals overlapping with zero difference.

Conclusions:

A protocol is presented for a national whole-of-patient-population retrospective cohort study designed to describe the safety and effectiveness of erlotinib and gefitinib during their first decade of routine use in NZ for treating EGFR mutation-positive lung cancer. This validation sub-study demonstrated the feasibility and validity of using national electronic health databases and methodologies for determining patient eligibility and identifying the study outcomes and variables proposed in the study protocol.