Trends and inequalities in the burden of mortality in Scotland 2000–2015

Background
Cause-specific mortality trends are routinely reported for Scotland. However, ill-defined deaths are not routinely redistributed to more precise and internationally comparable categories nor is the mortality reported in terms of years of life lost to facilitate the calculation of the burden of disease. This study describes trends in Years of Life Lost (YLL) for specific causes of death in Scotland from 2000 to 2015.
Methods
We obtained records of all deaths in Scotland by age, sex, area and underlying cause of death between 2000 and 2015. We redistributed Ill-Defined Deaths (IDDs) to more exact and meaningful causes using internationally accepted methods. Years of Life Lost (YLL) using remaining life expectancy by sex and single year of age from the 2013 Scottish life table were calculated for each death. These data were then used to calculate the crude and age-standardised trends in YLL by age, sex, cause, health board area, and area deprivation decile.
Results
Between 2000 and 2015, the annual percentage of deaths that were ill-defined varied between 10% and 12%. The proportion of deaths that were IDDs increased over time and were more common: in women; amongst those aged 1–4 years, 25–34 years and >80 years; in more deprived areas; and in the island health boards. The total YLL fell from around 17,800 years per 100,000 population in 2000 to around 13,500 years by 2015. The largest individual contributors to YLL were Ischaemic Heart Disease (IHD), respiratory cancers, Chronic Obstructive Pulmonary Disease (COPD), cerebrovascular disease and Alzheimer’s/dementia. The proportion of total YLL due to IHD and stroke declined over time, but increased for Alzheimer’s/dementia and drug use disorders. There were marked absolute inequalities in YLL by area deprivation, with a mean Slope Index of Inequality (SII) for all causes of 15,344 YLL between 2001 and 2015, with IHD and COPD the greatest contributors. The Relative Index of Inequality (RII) for YLL was highest for self-harm and lower respiratory infections.
Conclusion
The total YLL per 100,000 population in Scotland has declined over time. The YLL in Scotland is predominantly due to a wide range of chronic diseases, substance misuse, self-harm and increasingly Alzheimer’s disease and dementia. Inequalities in YLL, in both relative and absolute terms, are stark.

背景
苏格兰地区常规发布按病因分类的死亡率趋势报告，但目前尚未将死因不明的死亡病例常规重新分配至更精准、具备国际可比性的疾病类别中，也未通过减寿年数（Years of Life Lost, YLL）维度统计死亡率，以辅助疾病负担测算。本研究分析了2000至2015年苏格兰地区各类死因的减寿年数趋势。

方法
本研究收集了2000至2015年苏格兰地区全部死亡病例的记录，信息涵盖年龄、性别、地域及根本死因。研究采用国际公认的方法，将死因不明死亡病例（Ill-Defined Deaths, IDDs）重新归类至更精准且具临床意义的病因类别中。针对每一例死亡病例，基于2013年苏格兰生命表中按性别及单一年龄组划分的剩余预期寿命，计算其减寿年数。随后基于上述数据，按年龄、性别、病因、卫生委员会辖区以及区域贫困十等分位，分别核算减寿年数的粗趋势与年龄标化趋势。

结果
2000至2015年间，苏格兰地区死因不明死亡病例占年度总死亡数的比例在10%至12%之间波动。死因不明死亡病例的占比随时间推移呈上升趋势，且在以下人群/区域中更为常见：女性群体；1~4岁、25~34岁及80岁以上人群；贫困程度更高的区域；以及岛屿卫生委员会辖区。每10万人口的总减寿年数从2000年的约17800人年，降至2015年的约13500人年。对总减寿年数贡献最大的单病种分别为缺血性心脏病（Ischaemic Heart Disease, IHD）、呼吸道恶性肿瘤、慢性阻塞性肺疾病（Chronic Obstructive Pulmonary Disease, COPD）、脑血管疾病以及阿尔茨海默病/痴呆症。缺血性心脏病与脑卒中所致的总减寿年数占比随时间下降，而阿尔茨海默病/痴呆症及药物使用障碍所致的占比则有所上升。按区域贫困程度划分的减寿年数存在显著绝对不平等：2001至2015年，所有病因的平均斜率指数（Slope Index of Inequality, SII）为15344人年，其中缺血性心脏病与慢性阻塞性肺疾病的贡献占比最高。减寿年数的相对指数（Relative Index of Inequality, RII）在自残与下呼吸道感染病例中达到最高值。

结论
苏格兰地区每10万人口的总减寿年数随时间推移呈下降趋势。该地区的减寿年数主要源自多种慢性病、物质滥用、自残行为，且阿尔茨海默病与痴呆症的贡献占比逐年提升。减寿年数在相对与绝对维度上的不平等现象均十分显著。