Hwa Jeong Seo
Medical Informatics and health Technology (MIT), Department of Health Care Management, College of Social Science, Gachon University, Seongnam, Korea
Background: This study aimed to determine the effectiveness
of metformin as first line oral hypoglycemic agent in diabetes
patients in inhibiting cancer incidence, on the basis of the
sample cohort supplied by the National Health Insurance
Service, and to ascertain the effects of time-related bias on
the results.
Methods: A t-test was performed to compare the time taken
for cancer development between the compliant and
non-compliant metformin users and the non-metformin users.
Survival analyses for cancer patients, regarding
the period time until cancer incidence, were performed
according to metformin use through three models: mod- el 1
adjusted for age and sex; model 2 further adjusted for body
mass index, cholesterol, and smoking status; and model 3
further adjusted for hypertension.
Results: The odds ratio for cancer development was 1.11
times higher for the non-metformin users (6,997) than
for the metformin compliant users (16,132), which was
significant at the 0.1 significance level. The age, sex, body
mass index, cholesterol, smoking status, and hypertension-
adjusted hazard ratio was 0.86.
Conclusions: This study has confirmed that metformin is
effective in delaying cancer development for patients
at risk of cancer rather than in inhibiting cancer incidence
itself, by strict application of metformin exposure, with which
immortal time biases are controlled. It is therefore necessary
to manage compliance with an agent, as
well as to prescribe metformin for patients at high risk of
cancer, giving consideration to the risk factors for can-
cer development (old age, being male) instead of focusing
on metformin prescription, with the objective of in- hibiting
cancer development.
Korean J Health Promot 2022;22(1):40-47
Keywords: Diabetes mellitus, Neoplasms, Medication
adherence, Selection bias, Cohort studies |