以未設限機率權重修正醫療費用模型─健保資料中腸癌之實例研究

The uncensored probability adjusted cost model-an application in colorectal cancer

葉婉琳(Wan-Lin Yeh)

指導教授 ： 黃怡婷

國立臺北大學/商學院/統計學系/碩士(2010年)

摘要

由於社會年齡結構的改變，如何有效重新更合理的分配醫療資源變得非常重要。因此我們需要知道如何準確且有效地估計醫療費用。然而，在成本資料收集中常遇到個體提早離開研究而導致資料不完全的情況。傳統估計式忽略了無法觀測資料的部份因而可能產生有偏。Lin (1997)建議將研究期間分割成數個區間，並估計各區間成本再將其加總。更進一步，考量到未觀測資料， Lin (1997)及 Bang及Tsiatis (2000)分別提出利用存活機率和未設限機率倒數作為權重的權重估計式。本論文為比較在不同的模擬情境下，兩種權重方式所延伸的估計式的表現。

除此之外，醫療費用可能會受到多個共變數的影響。 Baser (2006)建議對於長期資料可以利用一般線性模型建構區間成本，其中刻劃個體間變異的隨機截距項是可以放進模型中的。更進一步，如同 Lin (1997)權重概念，我們建議由Cox比例危險模型所推估出的未設限機率倒數作為權重，並在模擬中評估權重前後模型的表現。最後，將本論文提出的模型應用至健保資料庫中大腸直腸癌病患資料。

關鍵字

設限成本 ； Kaplan Meier 估計方法 ； 機率倒數權重 (IPW) ； 最大限制概似方法 ； 混合模型 ； Cox比例危險模型

並列摘要

Owing to aging, how to efficiently distribute the limited resources becomes very important. In turn, we need to know how to estimate medical cost accurately and efficiently. However, it is common to have dropouts when collecting medical cost. The naive estimators ignoring the unobservable data may be biased. Lin (1997) suggested partitioning the study duration and estimating the cost of each interval and then constructing the estimate by summing up the cost from each interval. Furthermore, to take into account of the unobservable data, Lin (1997) and Bang and Tsiatis (2000) proposed weighted estimators that used the survival probability and uncensored probability as the weight, respectively. This thesis compares the performance of these estimators under various scenarios.

In addition, the medical cost may be related to many covariates. Baser (2006) suggested using the general linear model for the longitudinal data to model the partitioned cost, where a random intercept is included. This thesis extends the model to a more general parametric model. Furthermore, similar to the weight concept in Lin (1997), we suggest using the uncensored probability as the weight which is estimated from the Cox proportional hazards model. The performance of these models is evaluated using simulations. Finally, the proposed model is implemented on the data extracted from Health Insurance database for patients with the colorectal cancer.

並列關鍵字

Censoring ； Cost analysis ； Kaplan-Meier method ； Inverse probability weighted method ； Restricted maximum likelihood ； Mixed model Cox proportional hazards model.

參考文獻

difference between public and private general hospitals.

[1] Bang, H. and Tsiatis, A. A. (2000). Estimating medical costs

with censored data. Biometrika, 87, 329-343.

[2] Baser, O., Gardiner, J. C., Bradley, C. J., Yuce, H., Given, C.

(2006). Longitudinal analysis of censored medical cost data.