Temporal Trends in New Diagnoses of Colorectal Cancer with Obstruction, Perforation, or Emergency Admission in Ontario: 1993–2001

Abstract

Previous studies have shown that patients newly diagnosed with colorectal cancer requiring emergency admission to hospital or presenting with obstruction or perforation (defined here as OPE) have advanced disease. None of these studies, however, has evaluated temporal trends in these adverse outcomes, which may reflect screening failures. We evaluated temporal trends in the proportion of Ontario patients with a new diagnosis of colorectal cancer and OPE. Data were obtained from four sources: the Ontario Cancer Registry (OCR); the Canadian Institute for Health Information (CIHI) database, which contains diagnostic information on all patients discharged from hospitals; the Ontario Health Insurance Plan (OHIP) database, which records all physician claims in Ontario; and the Registered Persons Database, which contains demographic information on all Ontario residents covered under OHIP. We calculated the proportion of patients (>/=20 yr) with a new diagnosis of colorectal cancer recorded in CIHI who presented with OPE between 1993 and 2001. These patients were assigned to one of three cohort years: 1993-1995, 1996-1998, or 1999-2001. Those who received chemotherapy, radiotherapy, or palliative care before their first admission to hospital were excluded. We repeated the analysis using the number of OPE patients identified from CIHI in the numerator, and the number of patients (>/=20 yr) with a new diagnosis of colorectal cancer recorded in the OCR in the denominator. Adjusted risk of OPE was calculated using a logistic regression model. Between 1993 and 2001, 59,670 patients with a new diagnosis of colorectal cancer were recorded in the CIHI database and 54,103 in the OCR. The proportion of these patients with OPE recorded in the CIHI decreased significantly over time: 23.8% (95% CI = 23.2-24.4%) during 1993-1995, 19.4% (95% CI = 18.8-20.0%) during 1996-1998, and 18.1% (95% CI 17.6-18.6%) during 1999-2001 (a 24% relative decrease over time). The relative decrease calculated from OCR data was similar. The adjusted relative decrease in the proportion of patients with OPE during 1993-2001 was 31%. Much greater emphasis on screening is needed since approximately 20% of patients with a new diagnosis of colorectal cancer in 1999-2001 presented with OPE.