Association of Patient Proximity to Dermatologic Care With Melanoma Stage at Diagnosis and Outcome

This cohort study evaluates the association of proximity to dermatologic clinicians with stage at diagnosis and cancer-specific survival among adults with cutaneous melanoma in Iowa.


Introduction
2][3][4] However, previous studies did not include advanced practice practitioners (APPs), and their role in access to dermatologic care remains poorly understood.We aimed to determine the association between proximity to dermatologic clinicians and melanoma stage at diagnosis and cancer-specific survival (CSS) in Iowa, a largely rural state.

Methods
A retrospective cohort study was conducted using data from the Surveillance, Epidemiology, and End Results registry (eMethods in Supplement 1).The University of Iowa Human Subjects Office/ Institutional Review Board deemed this study as non-human participant research.We followed the STROBE reporting guideline.
Adults in Iowa with a single lifetime cutaneous melanoma diagnosis between January 2009 and December 2018 were included.Locations of full-time dermatologic clinicians (Ն3 days/week) from 2018 to 2020, including physicians and APPs (nurse practitioners and physician assistants), were identified through search engines, telephone calls to clinics, and cross-referencing data registries. 5,6r each zip code tabulation area (ZCTA) and clinician type (physicians, APPs, or combined), patient proximity to care was estimated by calculating road travel distance, time from the ZCTA centroid to nearest clinician, and clinician rate per 100 000 population.We categorized travel distance as less than 50 miles or 50 miles or more, time as less than 60 minutes or 60 minutes or more, and clinician rate as 0 or not 0.
Multinomial logistic and Cox proportional hazards regression models were used to evaluate the association of demographic, clinical, and geographic characteristics with stage and CSS.
Demographic and clinical characteristics associated with the outcome on univariable analysis and year of diagnosis were included in a multivariable model.Each geographic variable was added to the multivariable model and assessed for significance.For CSS, time was calculated from diagnosis to death from cancer.Patients who died of other causes were censored at death; patients who were still alive were censored at last follow-up.Statistical testing was 2-sided and assessed for significance at the 5% level using SAS 9.4 (SAS Institute).

Results
We

Discussion
Proximity to dermatologic care was not associated with melanoma stage at diagnosis or survival across multiple geographic measures.Previous studies [1][2][3] varied in geographic measures used, and proximity's role in access may be decreasing.Although most ZCTAs had no dermatologic clinicians, more than 93% of patients still lived within driving distance.Additionally, APPs composed more than 50% of the workforce and may be a source of extended access.
A study limitation was using clinician presence from 2018 to 2020 as a proxy because it was unfeasible to accurately capture presence for each diagnostic year.There was little evidence to suggest clinician presence changed significantly to introduce bias.Lack of proximity to clinicians may not be as critical a barrier to care as previously thought, warranting further studies.

Table 2 .
Association Between Covariates and Melanoma Stage at Diagnosis and Cancer-Specific Survival Presence of a full-time clinician in the ZCTA was not associated with melanoma stage at diagnosis after adjusting for age, sex, marital status, and year of diagnosis.
a Complete case analysis was based on N = 4887.bComplete case analysis was based on N = 4883.c d Presence of a full-time clinician in the ZCTA was not significantly associated with CSS after adjusting for age, sex, marital status, diagnosis year, melanoma stage, receipt of surgery, radiation, chemotherapy, and biological response modifiers.