Clustering Asian and North African Countries According to Trend of Colon and Rectum Cancer Mortality Rates: an Application of Growth Mixture Models

Background: Colorectal cancer is the second most common cause of cancer death with half a million deathsper year. Incidence and mortality rates have demonstrated notable changes in Asian and African countriesduring the last few decades. In this study, we first aimed to determine the trend of colorectal cancer mortalityrate in each Institute for Health Metrics and Evaluation (IHME) region, and then re-classify them to find morehomogenous classes. Materials and
Methods: Our study population consisted of 52 countries of Asia and NorthAfrica in six IHME pre-defined regions for both genders and age-standardized groups from 1990 to 2010.We firstapplied simple growth models for pre-defined IHME regions to estimate the intercepts and slopes of mortalityrate trends. Then, we clustered the 52 described countries using the latent growth mixture modeling approachfor classifying them based on their colorectal mortality rates over time.
Results: Statistical analysis revealed thatmales and people in high income Asia pacific and East Asia countries were at greater risk of death from colonand rectum cancer. In addition, South Asia region had the lowest rates of mortality due to this cancer. Simplegrowth modeling showed that majority of IHME regions had decreasing trend in mortality rate of colorectalcancer. However, re-classification these countries based on their mortality trend using the latent growth mixturemodel resulted in more homogeneous classes according to colorectal mortality trend.
Conclusions: In general,our statistical analyses showed that most Asian and North African countries had upward trend in their colorectalcancer mortality. We therefore urge the health policy makers in these countries to evaluate the causes of growingmortality and study the interventional programs of successful countries in managing the consequences of thiscancer.