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Treatment of colorectal cancer

Thomas Nickelsen  


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Accepted by: Sundhedsvidenskabelige København
Defended on: September 27, 2005
Official opponents: Peer Wille-Jørgensen , Lars Påhlman , Henrik Toft Sørensen
Tutors: Torben Jørgensen , Ole Kronborg

Published in the PhD Database: August 31, 2007


English abstract
Through the nineties there was a debate on the quality of the treatment of CRC (Colorectal Cancer) in Denmark. Statistics showed that the survival was lower compared to that in other Nordic countries. This lead to the foundation of the DCCG-database (Danish Colorectal Cancer Group), including all CRC patients with a first time adenocarcinoma. This systematic registration of all patients makes it possible to monitor and improve the treatment and to compare the departments.
The aims of this thesis were to evaluate the validity and completeness of the DCCG-database, to compare 30-day mortality between the departments with and without adjustment for case-mix, and to identify lifestyle factors with impact on 30-day mortality and four common complications. Finally associations between structural factors in the departments and 30-day complications or mortality were studied.
Initially a 5% (n=87) sample of patients from 2001 was re-entered to the database using the patient records from the departments. The validity was satisfying with mean κ-values between 0.55 and 0.67. The data quality was considered sufficient for further analyses.
Data originated from the national DCCG-database, the National Patient Registry, the Central Office for Civil Registration and a questionnaire concerning structural factors sent to all departments. All patients in the database operated between 1 May 2001 and 31 December 2002 were included (n=5187) and the database had a completeness of 89.2%.
The mean 30-day mortality after CRC operation was 9.9%. This was a higher rate than in most other studies, but no comparable nationwide study was found, and the difference may be explained by selection bias. Significant differences in 30-day mortality were found between the departments operating colorectal cancer (CRC) with and without adjusting for case-mix. Some of the differences might be caused by differences in case-mix factors not included, primarily lifestyle-factors.
One or more of the lifestyle factors (Body Mass Index ≥ 30kg/m2 (BMI), smoking, drinking more than 60 g alcohol/day, self perceived physical fitness (SPPF)) had significant impact on 30-day mortality, complications in general or one or more of four complications (impaired wound healing, anastomotic leakage, deep wound infection, and thrombosis). In a population with no exposure to smoking, BMI below 30 kg/m2, alcohol intake below 60 gram/day and SPPF at or above average there would be 23% less complications and 64% less mortality within 30 days. Although the analyses include only 43 ¿ 69% of the data caused by low completeness of the patient data, we believe the lifestyle factors to have substantial impact on the outcome after CRC.
Of the analysed structural variables, only the mean surgical volume of the surgeon had significant impact on the morbidity in rectal surgery. No structural factors were substantially related to mortality and morbidity in colonic surgery. The authors were surprised to find such low impact of structural factors, as these factors are important in accreditation and quality improvement. Possible explanations to the results are that Denmark is a small country with very homogeneous structure for the treatment of CRC leaving no room for differences, or that our choice of factors was irrelevant or sub optimally defined.
This thesis looks into factors with impact on the significant difference in 30-day mortality in the departments. It focuses on associations between the patient, the treatment, the organisation and the outcome. Structural factors had except from surgical volume of the rectal surgeon no substantial impact, in contrast to lifestyle factors. The thesis illustrates the possibilities to analyse and compare departments and to identify potential risk factors for mortality/morbidity by means of clinical databases. The importance of high validity and completeness is discussed.



Danish abstract
I 1990¿erne var der meget debat om kvaliteten af den danske behandling af kolorektal cancer (CRC). Mortalitetsstatistikker viste dårligere overlevelse i Danmark end i de øvrige nordiske lande. Dette ledte til grundlæggelsen af DCCG-databasen (Danish Colorectal Cancer Group), som registrerer alle CRC-patienter med en førstegangs adenocarcinom diagnose.
Formålene med denne ph.d. tese var at validere DCCG-databasen både med hensyn til dækningsgrad og datakvalitet, at sammenligne 30-dags mortaliteten mellem alle danske afdelinger justeret og ujusteret for case-mix samt at undersøge om livsstilsfaktorer har betydning for mortalitet og fire udvalgte hyppige komplikationer. Endelig skulle sammenhængen mellem strukturelle forhold på afdelingerne og 30-dags komplikationer og død undersøges.
Indledningsvist blev validiteten af data undersøgt i et randomiseret udtræk på 5% af patienter opereret i 2001. Analyserne på udtrækket viste gennemsnits κ-værdier mellem 0.55 til 0.67, og validiteten blev vurderet sufficient for de planlagte yderligere analyser.
Data til analyserne stammede fra DCCG-databasen, Landspatientregisteret, CPR-registeret og et spørgeskema om strukturelle faktorer sendt til alle afdelinger. Alle patienter opereret i perioden 1. maj 2001 til 31. december 2002 blev inkluderet fra DCCG-databasen (n=5187), og dækningsgraden var 89.2%.
Blandt alle opererede patienter var 30-dags mortaliteten 9.9%. Dette var højere end i de fleste andre studier, men der blev ikke fundet nogen direkte sammenlignelige landsdækkende opgørelser, og den højere danske mortalitet kan skyldes selektions bias. Der blev påvist signifikant forskel på 30-dags mortaliteten afdelingerne i mellem, både med og uden justering for case-mix. En del af forskellen kan formentligt tilskrives faktorer som ikke blev inddraget i case-mix, primært livsstilsfaktorerne. En eller flere af livsstilsfaktorerne (BMI ≥ 30kg/m2 (Body Mass Index), rygning, alkoholforbrug, selv vurderet fysisk form (SPPF)) havde signifikant betydning for 30-dages mortaliteten, komplikationer generelt og/eller en eller flere af fire hyppige komplikationer (nedsat sårheling, anastomoselækage, dyb sårinfektion og thromboser). I en population uden påvirkning af risikofaktorer (ingen rygning, BMI <30 kg/m2, alkohol ≤60 g/dag (5 genstande), SPPF ≥ middel) ville der være 23% færre komplikationer og 64% lavere 30-dags mortalitet (ætiologisk fraktion). Selv om analyserne kun inkluderer mellem 43% og 69% af patienterne på grund af lav dækningsgrad af patientspørgeskemaet, anser vi livsstilsfaktorer for at have en betydelig effekt på resultater af CRC-kirurgi.
Af de analyserede strukturvariable havde kun det gennemsnitlige antal operationer pr. kirurg betydning for udfaldet af rektumkirurgi. Ingen strukturfaktorer havde nær samme betydning indenfor kolonkirurgi. Det var ikke ventet med så ringe en effekt af strukturvariablene, da de udgør en vigtig del af akkreditering og kvalitetsudvikling. En mulig forklaring er, at Danmark er et lille land med en så stor ensartethed af behandlingen på CRC-området, at forskellene er for små til at kunne analyseres. En anden mulighed er, at vores valg og definition af de analyserede faktorer ikke var optimalt.
Denne tese undersøger faktorer af betydning for den signifikante forskel på 30-dags mortaliteten mellem afdelingerne. Den fokuserer på sammenhængen mellem patient, behandling, organisation og resultat. Strukturelle faktorer havde fraset antal operationer pr. rektalkirurg, kun ringe betydning, modsat livsstilsfaktorer. Tesen illustrerer mulighederne for en klinisk database med at analysere og sammenligne afdelingers resultater, samt identificere nye mulige risikofaktorer for død og komplikationer. Vigtigheden af en høj dækningsgrad og datakvalitet diskuteres.