The Concept and Application of the Joinpoint Regression Model in Analyzing the Time Trend in Epidemiological Studies (Case: Liver Cancer due to Alcohol Use in Iran)

Time trend analysis of factors such as disease and mortality rates is a crucial component of health planning for any community. It allows for a more accurate interpretation of changes over time. This study was conducted to examine the performance of the Joinpoint regression model in analyzing time trends.

This study aims to first provide a simplified understanding of the Joinpoint regression model and then demonstrate its application on data regarding the 30-year trends of liver cancer mortality due to alcohol consumption in Iran.

The results of the time trend analysis indicate that the age-standardized mortality rate of liver cancer due to alcohol use consumption has decreased by an average of 0.8% per year over the 30-year period in Iran (1990 to 2019). The projections also suggest that this declining trend will continue.

In general, the main advantage of the Joinpoint regression model over other models is its ability to identify periods where significant changes in trends have occurred. Based on the results, the mortality rate of liver cancer due to alcohol use consumption over the 30-year period in Iran can be divided into five periods with different rates of change.