Abstract A25: Effect of pre-existing conditions on bladder cancer diagnosis: A cohort study using electronic primary care records
Authors: Carney Madeline H. , Price Sarah , Shephard Elizabeth , Mounce Luke , Quiroga Myra , Hamilton Willie 
Published: August 2020

Abstract
Background: Existing comorbid diseases may delay the diagnosis of bladder cancer. This study tested two hypotheses. First, there is an association between existing comorbidity burden and advanced-stage cancer, where the conditions compete for clinical attention and cancer symptoms are overlooked. Second, there is an association between the presence of comorbid conditions that mimic the patient's first possible symptom of cancer and advanced-stage cancer, through symptom misattribution.
Methods: This population-based, observational study was set in The Clinical Practice Research Datalink (CPRD; a dataset of UK primary care medical records) with linkage to Public Health England National Cancer Registration and Analysis Service data. We studied adults (≥40 years) with an incident bladder cancer diagnosis (ICD10 code C67) between 01/01/2000 and 12/31/2015. CPRD records made in the year before cancer diagnosis were searched for codes indicating attendance for bladder cancer symptoms (hematuria, dysuria, and abdominal mass). CPRD records made in the 2 years before the earliest cancer symptom were searched for diagnostic codes for common comorbid conditions (e.g., diabetes and cardiovascular diseases) and for conditions sharing symptoms with bladder cancer (urinary tract infection, sexually transmitted disease, kidney disease, tuberculosis, sickle cell disease, nephrolithiasis, prostatitis, menorrhagia, endometriosis, benign prostatic hyperplasia, uterine fibroids, aortic aneurysm, and retention). The data were analyzed using logistic regression. The outcome variable was stage of bladder cancer diagnosis: advanced (3 or 4) vs. early (1 or 2). Explanatory variables included count of pre-existing comorbid conditions, and an “alternative-explanations” variable indicating when a patient's comorbid condition could explain their first possible bladder cancer symptom. The model adjusted for age, sex, and deprivation.
Results: The analysis included 1,469 (76.4% male) patients, of whom 270 (18.4%) had advanced-stage cancer. 1,178/1,469 (80.2%) patients (73.6% male) had 1 or more comorbid conditions. 616/1,469 (41.9%) patients (64.8% male) had alternative explanations for the first possible symptom of cancer. Women were more likely than men to be diagnosed with advanced-stage cancer (odds ratio 1.62; 95% confidence interval 1.20 to 2.18; p=0.001). Alternative explanations for the first possible symptom of bladder cancer were strongly associated with advanced-stage diagnosis similarly in men and women (1.69, 1.20 to 2.39, p=0.003). Count of conditions was not associated with stage at diagnosis (p=0.64).
Conclusion: Existing comorbid diseases that mimic the presentation of bladder cancer are associated with advanced stage at diagnosis. Women are more likely than men to be diagnosed with advanced-stage cancer, but the effect is not driven by alternative explanations.
Note: This abstract was not presented at the conference.
Citation Format: Madeline H. Carney, Sarah Price, Elizabeth Shephard, Luke Mounce, Myra Quiroga, Willie Hamilton. Effect of pre-existing conditions on bladder cancer diagnosis: A cohort study using electronic primary care records [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr A25.