Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore, Singapore.
PLoS One. 2011 Jan 20;6(1):e15603. doi: 10.1371/journal.pone.0015603.
Clostridium difficile infection (CDI) is an increasingly recognized nosocomial infection in Singapore. Surveillance methods include laboratory reporting of Clostridium difficile toxin assays (CDTA) or use of International Classification of Diseases, 9(th) Revision (ICD-9) discharge code 008.45. Previous US studies showed good correlation between CDTA and ICD-9 codes. However, the use of ICD-9 codes for CDI surveillance has not been validated in other healthcare settings.
We compared CDI rates based on CDTA to ICD-9 codes for all discharges in 2007 from our hospital to determine sensitivity and specificity of ICD-9 codes. Demographic and hospitalization data were analyzed to determine predictors for missing ICD-9 codes.
During 2007, there were 56,352 discharges. Of these, 268 tested CDTA-positive but only 133 were assigned the CDI ICD-9 code. A total of 141 discharges had the ICD-9 code; 8 were CDTA-negative, the rest were CDTA-positive. Community-acquired CDI accounted for only 3.2% of cases. The sensitivity and specificity of ICD-9 codes compared to CDTA were 49.6% and 100% respectively. Concordance between CDTA and ICD-9 codes was 0.649 (p<.001). Comparing concordant patients (CDTA+/ICD9+) to discordant patients (CDTA+/ICD9-), concordant patients were more likely to be over 50 years of age (OR 3.49, 95% CI 1.66-7.34, p = .001) and have shorter time from admission to testing (OR 0.98, 95% CI 0.97-0.99, p = .009).
Unlike previous studies in the US, ICD-9 codes substantially underestimate CDI in Singapore compared to microbiological data. Older patients with shorter time to testing were less likely to have missing ICD-9 codes.
艰难梭菌感染（CDI）是新加坡日益受到关注的医院获得性感染。监测方法包括实验室报告艰难梭菌毒素检测（CDTA）或使用国际疾病分类，第 9 版（ICD-9）出院代码 008.45。以前的美国研究表明 CDTA 与 ICD-9 代码之间具有良好的相关性。然而，ICD-9 代码在其他医疗保健环境中用于 CDI 监测尚未得到验证。
我们比较了 2007 年我院所有出院患者的 CDTA 与 ICD-9 代码的 CDI 发生率，以确定 ICD-9 代码的敏感性和特异性。分析人口统计学和住院数据，以确定 ICD-9 代码缺失的预测因素。
2007 年期间，共有 56352 例出院患者。其中，268 例 CDTA 检测阳性，但仅有 133 例被分配 CDI ICD-9 代码。共有 141 例出院患者有 ICD-9 代码；8 例 CDTA 阴性，其余为 CDTA 阳性。社区获得性 CDI 仅占病例的 3.2%。与 CDTA 相比，ICD-9 代码的敏感性和特异性分别为 49.6%和 100%。CDTA 与 ICD-9 代码的一致性为 0.649（p<.001）。比较 CDTA+/ICD9+ 和 CDTA+/ICD9-患者，CDTA+/ICD9+患者更可能年龄超过 50 岁（OR 3.49，95%CI 1.66-7.34，p =0.001），且从入院到检测的时间更短（OR 0.98，95%CI 0.97-0.99，p =0.009）。
与美国之前的研究不同，与微生物数据相比，新加坡的 ICD-9 代码大大低估了 CDI 的发生率。检测时间较短的老年患者更不可能缺少 ICD-9 代码。
