目標：評估台灣使用自動化編碼系統與國際疾病分類第十版選擇原死因（新制）對於死因統計之影響。方法：本研究將2007年所有死亡個案同時使用新制與舊制（編碼人員使用國際疾病分類第九版人工選擇原死因）進行編碼，計算死因別可比較性比值（新制死亡數/舊制死亡數）。本研究探討改制後對兩種死因統計列表清單之影響，一是主要（十大）死因排序列表， 二是美國國立衛生統計中心使用的113分類項列表。結果：使用新制與舊制前三名死因排序相同，但是死亡數卻有差異。新制比舊制死亡數，惡性腫瘤少2,544人，心臟疾病多2,274人，腦血管疾病少2,144人。舊制支氣管炎肺氣腫氣喘死亡數為1,165人排名第十二，新制慢性下呼吸道疾病死亡數5,314人排名第七。新制/舊制死亡數比值大於2.0的死因是敗血症（2.751），病毒性肝炎（2.385）與本態性高血壓及高血壓性腎臟疾病（2.102）。比值小於0.7的死因是阿茲海默症（0.250）與支氣管炎（0.638）。結論：本雙軌編碼研究指出，造成某些死因別死亡數新制與舊制差異較大的原因有兩個：一是對應統計列表死因分類項涵蓋編碼的詳細度與範圍差異不同造成，二是台灣不少死亡證明書開具者習慣將明確死因診斷填在第二或第三個診斷，造成編碼人員與自動化編碼系統的判斷不同。建議分析台灣2008年前後死因別死亡率趨勢時，首先要確認所要探討的對應統計列表死因分類項涵蓋編碼的詳細度與範圍，新舊制是否有很大差異；二是使用轉換比值進行調整；三是使用多重死因分析進行補充。

Objectives: To assess the effects of implementing an automated coding system and the International Classification of Disease (ICD) 10th Revision (ICD-10) on mortality statistics in Taiwan. Methods: We used a new automated coding system based on ICD-10 (automatic ICD- 10) to assign the underlying cause of death (UCOD) for all deaths occurring in 2007. We then compared the number of deaths according to automatic ICD-10 with that coded manually by coders according to ICD-9 (manual ICD-9). The comparability ratio (CR, automatic ICD-10/ manual ICD-9) for a specific cause of death (COD) category was calculated. We assessed the impact on two mortality tabulation lists: the main (10 leading) tabulation list and the 113-category tabulation list used by the US National Center for Health Statistics. Results: The three leading CODs were the same according to both methods: malignant neoplasm, heart diseases, and cerebrovascular diseases. However, compared with manual ICD-9, automatic ICD-10 recorded 2,544 more deaths for malignant neoplasm, 2,274 more deaths for heart diseases, and 2,144 fewer deaths for cerebrovascular diseases. In all, 1,165 deaths were recorded under the bronchitis, emphysema, and asthma category, which ranked 12th according to manual ICD-9. By contrast, 5,314 deaths were recorded under the chronic lower respiratory disease category, which ranked 7th according to automatic ICD-10. Three CODs had CR > 2: septicemia (2.751), viral hepatitis (2.385), and essential hypertension and hypertensive renal disease (2.102). By contrast, two CODs had CR < 0.7: Alzheimer’s disease (0.250) and chronic and unspecified bronchitis (0.638). Conclusions: The results of this bridge coding study indicated large differences between the new and old methods in some COD categories. Two possible reasons are identified for this discrepancy. First, the level and range of codes included in the corresponding tabulation COD categories were different. Second, many medical certifiers recorded more specific COD diagnoses as the second and third diagnoses, which resulted in differences in judgment between coders and the automated system when assigning the UCOD. We recommend three measures when examining cause-specific mortality trends before and after 2008 in Taiwan. First, large differences in the level and range of codes included in corresponding COD categories should be evaluated. Second, the CR should be used for adjustment. Third, multiple COD data should be analyzed as a complement.