Do Physician Patient Sharing Networks Impact Disparities in Access to Multidisciplinary Cancer Consultation for Early-Stage Lung Cancer? A SEER-Medicare Network Analysis

Abstract

To examine early-stage non-small cell lung cancer (NSCLC) patient and physician network characteristics associated with receipt of multidisciplinary cancer consultations (MDCCs), defined as an encounter with both a surgeon and a radiation oncologist after diagnosis. We tested the hypothesis that physician roles in patient-sharing networks can modify disparities in access to surgical and radiotherapy care. Specifically, we investigated the role of "linchpin physicians" using a novel network measure that assesses the extent to which a physician is the sole type of specialist in their physician patient sharing network, and the association of these physicians on patterns of care. The study cohort included patients diagnosed with stage I/IIA NSCLC in 2016-17 using Surveillance, Epidemiology and End Results (SEER)-Medicare data. We assembled a physician patient-sharing network using all NSCLC patient encounters between 3 months prior to and 12 months following diagnosis. We weighted physicians' patient-sharing ties by the number of shared patients and calculated physician's linchpin scores as a continuous variable measuring the extent to which a physicians' peers in the network lack ties to others of the same specialty as the focal physician. Physicians in the top 15%ile were considered a linchpin specialist. We then derived the proportion of linchpin surgeons or radiation oncologists per hospital referral region (HRR). We assessed patient characteristics including age, sex, race, ethnicity, cancer stage, comorbidity index, rurality, and socioeconomic status (SES). The study outcome was a surgical, radiation oncology, or MDCC in the 2 months following diagnosis. We then performed multivariable logistic regressions (MLR) to assess whether linchpins modified disparities in MDCC. Of 6,148 patients in the study, 12% received a MDCC, 28% only saw a radiation oncologist, 33% only saw a surgeon, and 27% saw neither for 2 months after diagnosis. On MLR, Hispanic patients were significantly less likely than White patients to receive consultations with a radiation oncologist, while patients in lowest SES quintile were significantly less likely to receive a surgical consultation than those in the highest SES. The proportion of linchpin surgeons and radiation oncologists per HRR was negatively associated with receipt of MDCC (OR low vs high [95% CI] = 0.75 [0.66 to 0.86]; 0.70 [0.61 to 0.80, respectively), but our regressions did not show that any demographic or SES disparities were modified by linchpin specialists. Linchpin specialists do not impact known disparities in access to cancer consultations. Identifying additional system-level factors that contribute to disparities in cancer consultations may lead to policy insights aimed at reducing unwarranted variation in care.