Wu Eric Q, Birnbaum Howard, Kang Yoon Jun, Parece Andrew, Mallett David, Taitel Haya, Evans Robert J
Analysis Group, Inc., Boston, MA 02199, USA.
Curr Med Res Opin. 2006 Mar;22(3):495-500. doi: 10.1185/030079906X80431.
Interstitial cystitis (IC) is often misdiagnosed as one of several other conditions manifesting similar symptoms. This analysis assesses the potential extent of IC misdiagnosis while considering concomitant conditions in a managed care population and identifies predictors of IC diagnosis.
Administrative insurance claims data covering 1.7 million lives (1999-2003) were analyzed. Insurance enrollees with >or= 1 IC diagnosis (ICD-9-CM of 595.1x) were identified as IC patients. A random sample of non-IC controls was selected using a 10:1 matching ratio. Six-month incidence rates of 'commonly misdiagnosed conditions', (overactive bladder, urinary tract infection, chronic pelvic pain, endometriosis, prostatitis) were compared before and after patients' initial IC diagnosis and the reduction in incidence rate of commonly misdiagnosed conditions was used as a suggestive measure of the extent of IC misdiagnosis. The Kaplan-Meier method was used to assess the extent that commonly misdiagnosed conditions were predictors of subsequent IC. A Cox Proportional Hazards regression model (that adjusts for patient demographics, concomitant and misdiagnosed conditions) was used to estimate the hazard ratio (HR) of these conditions. Similar analyses were performed for the 'commonly concomitant conditions' (fibromyalgia, irritable bowel syndrome, vulvodynia).
There were 992 IC patients and 9920 controls identified. The reduced incidence of commonly misdiagnosed conditions after initial IC diagnosis suggests that the misdiagnosis rate could be as high as 38% within the 6-month period before initial IC diagnosis.
Diagnoses of commonly misdiagnosed conditions are significant predictors of future IC diagnosis. When overlooked, potential misdiagnosis of IC can lead to underestimation of the true prevalence of IC. Similarly, diagnoses of commonly concomitant conditions are significant predictors of future IC diagnosis. These initial findings based on claims data suggest hypotheses for further investigation with clinical data. These results suggest more consideration of IC as a diagnosis is warranted, especially when certain diagnoses are repeatedly made and the resulting treatments do not alleviate the patient's symptoms.
间质性膀胱炎（IC）常被误诊为其他几种表现出相似症状的疾病之一。本分析评估了在管理式医疗人群中考虑合并症的情况下IC误诊的潜在程度，并确定IC诊断的预测因素。
分析了涵盖170万人（1999 - 2003年）的行政保险理赔数据。将诊断为≥1次IC（国际疾病分类第九版临床修订本编码为595.1x）的保险参保者确定为IC患者。以10:1的匹配比例选取非IC对照的随机样本。比较患者初次IC诊断前后“常见误诊疾病”（膀胱过度活动症、尿路感染、慢性盆腔疼痛、子宫内膜异位症、前列腺炎）的六个月发病率，并将常见误诊疾病发病率的降低用作IC误诊程度的提示性指标。采用Kaplan - Meier方法评估常见误诊疾病作为后续IC预测因素的程度。使用Cox比例风险回归模型（对患者人口统计学特征、合并症和误诊疾病进行调整）来估计这些疾病的风险比（HR）。对“常见合并症”（纤维肌痛、肠易激综合征、外阴痛）进行了类似分析。
共识别出992例IC患者和9920例对照。初次IC诊断后常见误诊疾病发病率降低，这表明在初次IC诊断前的6个月内误诊率可能高达38%。
常见误诊疾病的诊断是未来IC诊断的重要预测因素。当被忽视时，IC的潜在误诊可能导致对IC真实患病率的低估。同样，常见合并症的诊断也是未来IC诊断的重要预测因素。这些基于理赔数据的初步发现为进一步利用临床数据进行研究提出了假设。这些结果表明，尤其在某些诊断反复做出且所采用的治疗未能缓解患者症状时，有必要更多地考虑将IC作为一种诊断。
