Application of propensity score model to examine the prognostic significance of lymph node number as a care quality indicator.
OBJECTIVE
There is a controversy about whether lymph node yield can be used as a proxy of quality care for patient with colorectal cancer. We aim to use propensity score models to investigate the association between lymph node number and long-term survival for colorectal cancer patients.


METHODS
Taiwan Cancer Database was employed to review all patients with newly diagnosed colorectal cancer from 2003 to 2005. Exclusion criteria included those patients with stage IV disease or without information of lymph node. Propensity score models (examined lymph node >12 or <12 as dependent variable) were applied to group of patients with Stage II or Stage III disease and primary end point was 5-year survival (and mortality). We also report results of Stage I-III for comparison.


RESULTS
We identified 15,731 newly diagnosed colorectal cancers during study period, among which a total of 10,517 colorectal cancer patients treated at 32 hospitals fulfilled the inclusion criteria. Pathology reports of about 63 % (6658/10517) patients revealed lymph node retrieval >12. After propensity score matching, there were 2888, 1079, 1094 pairs recruited for Stage I-III, Stage II and Stage III, respectively. According to analysis of these matched pairs, the 5-year risk adjusted overall mortality were lower for lymph node examined ≥12 than <12 among Stage II (24.3% vs. 31.1%, p=0.012) and Stage I-III (20.8% vs. 23.6%, p=0.003), but insignificant for Stage III (40.2% vs. 45.6%, p=0.073). Similar situation happened with regard to disease-free and disease-specific mortality.


CONCLUSIONS
For patients with colorectal cancer undergoing colorectal surgery, the quality metric of lymph node is associated with significantly better 5-year survival except for Stage III disease.
Department of General Surgery, Zhongxing Branch, Taipei City Hospital, Graduate Institute of Health Policy and Management, College of Public Health, National Taiwan University Hospital, No.17 Suchow Road,Taipei, Taiwan.
Yun-Jau
YJ
Chang
Li-Ju
LJ
Chen
Yao-Jen
YJ
Chang
Kuo-Piao
KP
Chung
Mei-Shu
MS
Lai
D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D057216:Propensity Score; D019984:Quality Indicators, Health Care; D013624:Taiwan / Q000453:epidemiology