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Patient Demographic Factors Associated with Radiation Cystitis Development Following Radiation for Prostate Cancer
Remington T. Lim, MD¹, Ernie Shippey, MS², Andrew P. Loehrer, MD, MPH¹, Lawrence M. Dagrosa, MD¹, Jay C. Buckey Jr., MD¹, Rachel A. Moses, MD, MPH¹.
¹Dartmouth Health, Lebanon, NH, USA, ²Vizient Center for Advanced Analytics, Chicago, IL, USA.

BACKGROUNDChronic Radiation Cystitis (RC) may occur several months to years after completing pelvic malignancy radiotherapy. It manifests in hematuria and bothersome cystitis symptoms, often requiring unplanned healthcare interventions. Prior studies evaluating RC may be limited by sample size, short-term follow up, and homogeneous populations. Given the growing number of pelvic malignancy survivors, understanding the rate of developing RC is important. The purpose of this study is to evaluate contemporary 5-year rates of RC development and associated patient demographic factors following radiation for prostate cancer.
METHODSA retrospective cohort study of adult male prostate cancer patients with a minimum of 5 years of follow up were identified in the Vizient database via ICD-9 and ICD-10 diagnosis codes. Using CPT and ICD codes, rates of RC after index radiation completion were identified. Patient demographic factors including age, sex, race, ethnicity, insurance coverage, and socioeconomic status defined by neighborhood were collected. Multivariable logistic regression models to evaluate factors associated with RC development were used.
RESULTS Between 2014 and 2018, 143,567 adult men were identified who received primary prostate cancer radiation therapy. Approximately 98% (140,190/143,567) had localized, non-metastatic disease. More than 20% (30,415/143,567) developed RC a median of 23.6 months (Interquartile Range 9.1-38.4 months) following radiation treatment with demographics listed in Table 1. Patient factors associated with RC (Table 2) included older age, metastatic disease, Black race, Asian race, Hispanic ethnicity, Medicare coverage, Medicaid insurance, and living in a more vulnerable neighborhood.
CONCLUSIONSIn a large cohort of patients with at least 5 years follow up we found greater than 20% acquired an RC diagnosis. In this cohort, Black, Asian, and Hispanic race/ethnicity as well as residence in more vulnerable neighborhoods were associated with higher odds of developing RC. Further research is needed to better understand RC development and management.
Table 1: Demographics

Demographics		Radiation	Group %
		n = 143,567	%
Age	<55 (ref)	6,577	4.6%
	55-64	34,693	24.2%
	65-74	64,852	45.2%
	≥75	37,445	26.1%
Race	White (ref)	105,960	73.8%
	Black	23,148	16.1%
	Asian	3,107	2.2%
	Other/unknown	11,352	7.9%
Ethnicity	Hispanic	6,826	4.8%
	Other/unknown (ref)	136,741	95.2%
Primary payer	Medicare	86,190	60.0%
	Medicaid	5,332	3.7%
	Commercial/private (ref)	41,694	29.0%
	Other	10,351	7.2%
Vizient Vulnerability Index	Quartile 1 (ref)	46,882	32.7%
	Quartile 2	42,713	29.8%
	Quartile 3	23,457	16.3%
	Quartile 4 - Most Vulnerable neighborhoods	30,515	21.3%
Metastasis	Yes	3,377	2.4%
	No	140,190	97.6%
Radiation Cystitis	Yes	31,348	21.8%

Table 2: Patient Demographic Factors Associated with Radiation Cystitis

Patient Factors		OR	95% CI		P–value
Age	55-64 (55 ref)	1.19	1.17	1.22	<.01
	65-74	1.23	1.20	1.26	<.01
	≥75	2.06	2.01	2.12	<.01
Race	White (ref)
	Black	1.25	1.23	1.27	<.01
	Asian	1.11	1.07	1.15	<.01
	Other/unknown	0.84	0.82	0.86	<.01
Ethnicity	Hispanic	1.54	1.51	1.58	<.01
	Other/unknown (ref)
Primary payer	Commercial/private (ref)
	Medicare	1.43	1.41	1.46	<.01
	Medicaid	1.83	1.78	1.88	<.01
	Other	1.11	1.08	1.14	<.01
Vulnerability Index	Quartile 1 (ref)
	Quartile 2	1.06	1.05	1.08	<.01
	Quartile 3	1.11	1.09	1.13	0.13
	Quartile 4 - Most Vulnerable neighborhoods	1.23	1.21	1.25	<.01
Metastasis	Yes	1.61	1.55	1.68	<.01
	No (ref)
	OR: Odds Ratio, CI = Confidence Interval, ref = reference,

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