Is cancer stage data missing completely at random? A report from a large population-based cohort of non-small cell lung cancer

Andrew G Robinson; Paul Nguyen; Catherine L Goldie; Matthew Jalink; Timothy P Hanna

doi:10.3389/fonc.2023.1146053

Is cancer stage data missing completely at random? A report from a large population-based cohort of non-small cell lung cancer

Front Oncol. 2023 Apr 4:13:1146053. doi: 10.3389/fonc.2023.1146053. eCollection 2023.

Authors

Andrew G Robinson^{1

2}, Paul Nguyen³, Catherine L Goldie⁴, Matthew Jalink^{1

5}, Timothy P Hanna^{1

2

5}

Affiliations

¹ Division of Cancer Care and Epidemiology, Queen's Cancer Research Institute, Kingston, ON, Canada.
² Department of Oncology, Queen's University, Kingston, ON, Canada.
³ ICES, Queen's University, Kingston, ON, Canada.
⁴ School of Nursing, Queen's University, Kingston, ON, Canada.
⁵ Department of Public Health Sciences, Queen's University, Kingston, ON, Canada.

Abstract

Introduction: Population-based datasets are often used to estimate changes in utilization or outcomes of novel therapies. Inclusion or exclusion of unstaged patients may impact on interpretation of these studies.

Methods: A large population-based dataset in Ontario, Canada of non-small cell lung cancer patients was examined to evaluate the characteristics and outcomes of unstaged patients compared to staged patients. Multivariable Poisson regression was used to evaluate differences in patient-level characteristics between groups. Kaplan-Meier estimates of survival and log-rank statistics were utilized.

Results: In our Ontario cohort of 51,152 patients with NSCLC, 11.2% (n=5,707) were unstaged, and there was evidence that stage data was not missing completely at random. Those without assigned stage were more likely than staged patients to be older (RR [95%CI]), (70-79 vs. 20-59: 1.51 [1.38-1.66]; 80+ vs. 20-59: 2.87 [2.62-3.15]), have a higher comorbidity index (Score 1-2 vs 0: 1.19 [1.12-1.27]; 3 vs. 0: 1.49 [1.38-1.60]), and have a lower socioeconomic class (4 vs. 1 (lowest): 0.91 [0.84-0.98]; 5 vs. 1 (lowest): 0.89 [0.83-0.97]). Overall survival of unstaged patients suggested a mixture of early and advanced stage, but with a large proportion that are probably stage IV patients with more rapid death than those with reported stage IV disease.

Conclusion: In this case study, evaluation of stage-specific health care utilization and outcomes for staged patients with stage IV disease at the population level may have a bias as a distinct subset of stage IV patients with rapid death are likely among those without a documented stage in administrative data.

Keywords: administrative data; cancer stage; missing data; non-small cell lung cancer; population-based.

Grants and funding

This study was supported by ICES, which is funded by an annual grant from the Ontario Ministry of Health (MOH) and the Ministry of Long-Term Care (MLTC). TH holds a research chair provided by the Ontario Institute for Cancer Research through funding provided by the Government of Ontario (#IA-035). Parts of this material are based on data and information compiled and provided by: MOH, MLTC, CIHI, CCO, ORG and Statistics Canada. The analyses, conclusions, opinions and statements expressed herein are solely those of the authors and do not reflect those of the funding or data sources; no endorsement is intended or should be inferred. Parts of this material are based on data and/or information compiled and provided by CIHI. However, the analyses, conclusions, opinions and statements expressed in the material are those of the author(s), and not necessarily those of CIHI. Parts of this material are based on data and information provided by Cancer Care Ontario (CCO). The opinions, results, view, and conclusions reported in this paper are those of the authors and do not necessarily reflect those of CCO. No endorsement by CCO is intended or should be inferred. Parts of this report are based on Ontario Registrar General (ORG) information on deaths, the original source of which is Service Ontario. The views expressed therein are those of the author and do not necessarily reflect those of ORG or the Ministry of Government Services.