(037) Association of multimorbidity intervals with the risk of mortality among people living with diabetes: a territory-wide nested case-control study

Background: The first study to investigate and quantify the impacts of the length of time interval between diabetes and subsequent multimorbidity on the risk of mortality among patients living with diabetes.

Objectives: The study aims to examine whether, and to what extent, the time interval between first-diagnosed diabetes and a second chronic disease may be associated with the risk of mortality. In this study, we hypothesize an inverse association between the multimorbidity interval and mortality risks.

Methods:

Data sources:
This study obtained data from Hong Kong Clinical Data Analysis and Reporting System, where the demographic information, diagnosis records, medicine records and death registrations of patients are collected for the study.

Study design:
We conducted a territory-wide nested case-control study. The death of participants with multimorbidity is adopted as the outcome of the study. The underlying cohort included patients first diagnosed with diabetes from January 1, 2010 to December 31, 2012 and subsequently identified to have another chronic condition as of December 31, 2019. Patients with any chronic conditions 2 years before the diabetes diagnosis were excluded. Patients with demographic information loss or with age less than 18 were excluded.

Case and control participant selection:
We extracted those who died after developing multimorbidity as case participants. We defined the time interval from the date of developing multimorbidity (day 0) to the death date (index date) as survival period of case participants. We randomly selected 4 patients with the same age, sex, and second chronic condition who had not died after going through the same survival period of the case participants as the control participants to be matched with the case participants.

Exposure:
The multimorbidity interval, measured by year, is defined as the time interval from the date of diabetes diagnosis to the date of developing multimorbidity.

Statistical analysis:
Conditional logistic regression was used to estimate the adjusted odds ratio of death. Sub-group analysis was conducted specifically in men, women, those aged 65 years or more, and those were younger than 65 years. Stratified analysis was conducted for each of the second chronic conditions.

Results: Conditional logistic regression showed that overall, the risk of mortality reduces by 19% with the extension of multimorbidity interval by one year [95% CI 17%-21%]. Similar associations were estimated in sub-group analysis and stratified analysis.

Conclusions: We found that delayed multimorbidity incidence among diabetes patients may be related to a lower risk of mortality, with approximately 20%-decrease associated with one year of delayed multimorbidity.