Effect of pre-existing conditions on bladder cancer stage at diagnosis: a cohort study using electronic primary care records in the UK.

backgroundPre-existing concurrent medical conditions (multimorbidity) complicate cancer diagnosis when they provide plausible diagnostic alternatives for cancer symptoms.

aimTo investigate associations in bladder cancer between: first, pre-existing condition count and advanced-stage diagnosis; and, second, comorbidities that share symptoms with bladder cancer and advanced-stage diagnosis. DESIGN AND

settingThis observational UK cohort study was set in the Clinical Practice Research Datalink with Public Health England National Cancer Registration and Analysis Service linkage.

methodIncluded participants were aged ≥40 years with an incident diagnosis of bladder cancer between 1 January 2000 and 31 December 2015, and primary care records of attendance for haematuria, dysuria, or abdominal mass in the year before diagnosis. Stage at diagnosis (stage 1 or 2 versus stage 3 or 4) was the outcome variable. Putative explanatory variables using logistic regression were examined, including patient-level count of pre-existing conditions and 'alternative-explanations', indicating whether pre-existing condition(s) were plausible diagnostic alternatives for the index cancer symptom.

resultsIn total, 1468 patients (76.4% male) were studied, of which 399 (35.6%) males and 217 (62.5%) females had alternative explanations for their index cancer symptom, the most common being urinary tract infection with haematuria. Females were more likely than males to be diagnosed with advanced-stage cancer (adjusted odds ratio [aOR] 1.62; 95% confidence interval [CI] = 1.20 to 2.18;

conclusionAlternative explanations were associated with advanced-stage diagnosis of bladder cancer. Females were more likely than males to be diagnosed with advanced-stage disease, but the effect was not driven entirely by alternative explanations.