Department of Health Policy and Management, Seoul National University College of Medicine, Seoul, South Korea.
Department of Health Policy and Management, Jeju National University College of Medicine and Graduate School of Medicine, Jeju, South Korea.
Popul Health Metr. 2020 Jul 3;18(1):3. doi: 10.1186/s12963-020-00210-7.
This study aimed to compare three small-area level mortality metrics according to urbanity in Korea: the standardized mortality ratio (SMR), comparative mortality figure (CMF), and life expectancy (LE) by urbanity.
We utilized the National Health Information Database to obtain annual small-area level age-specific numbers of population and deaths in Korea between 2013 and 2017. First, differences in the SMR by urbanity were examined, assuming the same age-specific mortality rates in all small areas. Second, we explored the differences in ranking obtained using the three metrics (SMR, CMF, and LE). Third, the ratio of CMF to SMR by population was analyzed according to urbanity.
We found that the age-specific population distributions in urbanized areas were similar, but rural areas had a relatively old population structure. The age-specific mortality ratio also differed by urbanity. Assuming the same rate of age-specific mortality across all small areas, we found that comparable median values in all areas. However, areas with a high SMR showed a strong predominance of metropolitan areas. The ranking by SMR differed markedly from the rankings by CMF and LE, especially in areas of high mortality, while the latter two metrics did not differ notably. The ratio of CMF to SMR showed larger variations in small areas in rural areas, particularly in those with small populations, than in metropolitan and urban areas.
In a comparison of multiple SMRs, bias could exist if the study areas have large differences in population structure. The use of CMF or LE should be considered for comparisons if it is possible to acquire age-specific mortality data for each small area.
本研究旨在比较韩国三种小区域死亡率指标在城市化水平上的差异：标准化死亡率比（SMR）、比较死亡率（CMF）和城市化水平的预期寿命（LE）。
我们利用国家健康信息数据库，获取了韩国 2013 年至 2017 年每年小区域年龄别人口和死亡人数的年度数据。首先，假设所有小区域的年龄别死亡率相同，检查了城市化水平对 SMR 的差异。其次，我们探讨了三种指标（SMR、CMF 和 LE）的排名差异。第三，分析了按人口划分的 CMF 与 SMR 的比值。
我们发现，城市化地区的年龄别人口分布相似，但农村地区的人口结构相对较老。年龄别死亡率也因城市化水平而异。假设所有小区域的年龄别死亡率相同，我们发现所有地区的中位数都相当。然而，SMR 较高的地区大都市地区的比例较高。SMR 的排名与 CMF 和 LE 的排名明显不同，尤其是在死亡率较高的地区，而后两者的排名差异不大。CMF 与 SMR 的比值在农村地区的小区域中表现出较大的变化，尤其是在人口较少的地区，而在大都市和城市地区则变化不大。
在比较多个 SMR 时，如果研究区域的人口结构存在较大差异，可能存在偏差。如果有可能获得每个小区域的年龄别死亡率数据，则应考虑使用 CMF 或 LE 进行比较。
