Comorbid conditions delay diagnosis of colorectal cancer: a cohort study using electronic primary care records

Problem

Cancer survival in England is lower than the European average. The discrepancy is attributed in part to late diagnosis. There is relatively little research exploring associations between multimorbidity and cancer

diagnosis. Pre-existing non-cancer conditions may complicate and delay colorectal cancer diagnosis. We explored the associations between diagnostic interval, demographics and number of conditions, and investigated the relative effects of conditions that are unrelated to colorectal cancer, but could compete for clinical attention, and of conditions providing alternative explanations for key diagnostic features of cancer.

Approach

Incident cases (aged ≥40 years, 2007-2009) with colorectal cancer were identified in the Clinical

Practice Research Datalink, UK. Diagnostic interval was defined as time from first symptomatic

presentation of colorectal cancer to diagnosis. Comorbid conditions were classified as ‘competing

demands’ (unrelated to colorectal cancer) or ‘alternative explanations’ (sharing symptoms with

colorectal cancer). The association between diagnostic interval (log-transformed) and age, gender,

consultation rate, and number of comorbid conditions was investigated using linear regressions,

reported using geometric means.

Findings

Of the 4,512 patients included, 72.9% had ≥1 competing demand and 31.3% had ≥1 alternative

explanation. In the regression model, the numbers of both types of comorbid conditions were

independently associated with longer diagnostic interval: a single competing demand delayed

diagnosis by 10 days, and four or more by 32 days; and a single alternative explanation by 9 days.

For individual conditions, the longest delay was observed for inflammatory bowel disease (26 days;

95% CI 14-39).

Consequences

An increased time to diagnosis in colorectal cancer, ranging from 9 to 32 days, was associated with conditions that give a plausible diagnostic alternative, or that are unrelated to colorectal cancer, yet place competing demands at the time of

diagnosis. Effective clinical strategies are needed for shortening the diagnostic interval in the

presence of comorbidity, which should be particularly targeted at patients aged 80 years or older.