Physician social networks and variation in rates of complications after radical prostatectomy

Cooperation Improvement in an Integrated Healthcare Network: A Social Network Analysis

Background

Cooperation is a core feature of integrated healthcare systems and an important link in their value-creating mechanism. The premise is that providers who cooperate can promote more efficient use of health services while improving health outcomes. We studied the performance of an integrated healthcare system in improving regional cooperation.

Methods

Using claims data and social network analysis, we constructed the professional network from 2004 to 2017. Cooperation was studied by analyzing the evolution of network properties at network and physician practice (node) level. The impact of the integrated system was studied with a dynamic panel model that compared practices that participated in the integrated system versus nonparticipants.

Results

The regional network evolved favourably towards cooperation. Network density increased 1.4% on average per year, while mean distance decreased 0.78%. At the same time, practices participating in the integrated system became more cooperative compared to other practices in the region: Degree (1.64e-03, p = 0.07), eigenvector (3.27e-03, p = 0.06) and betweenness (4.56e-03, p < 0.001) centrality increased more for participating practices.

Discussion

Findings can be explained by the holistic approach to patients' care needs and coordination efforts of integrated healthcare. The paper provides a valuable design for performance assessment of professional cooperation.

Highlights

Using claims data and social network analysis, we identify a regional cooperation network and conduct a panel analysis to measure the impact of an integrated care initiative on enhancing professional cooperation.Physician practices participating in the integrated system became more cooperative and improved their influence in the regional network more than non-participating practices.Integrated healthcare systems effectively incentivize cooperation through a holistic approach to patient care needs and coordination efforts.

Protocol for the Pathways Study: a realist evaluation of staff social ties and communication in the delivery of neonatal care in Kenya

INTRODUCTION

The informal social ties that health workers form with their colleagues influence knowledge, skills and individual and group behaviours and norms in the workplace. However, improved understanding of these 'software' aspects of the workforce (eg, relationships, norms, power) have been neglected in health systems research. In Kenya, neonatal mortality has lagged despite reductions in other age groups under 5 years. A rich understanding of workforce social ties is likely to be valuable to inform behavioural change initiatives seeking to improve quality of neonatal healthcare.This study aims to better understand the relational components among health workers in Kenyan neonatal care areas, and how such understanding might inform the design and implementation of quality improvement interventions targeting health workers' behaviours.

METHODS AND ANALYSIS

We will collect data in two phases. In phase 1, we will conduct non-participant observation of hospital staff during patient care and hospital meetings, a social network questionnaire with staff, in-depth interviews, key informant interviews and focus group discussions at two large public hospitals in Kenya. Data will be collected purposively and analysed using realist evaluation, interim analyses including thematic analysis of qualitative data and quantitative analysis of social network metrics. In phase 2, a stakeholder workshop will be held to discuss and refine phase one findings.Study findings will help refine an evolving programme theory with recommendations used to develop theory-informed interventions targeted at enhancing quality improvement efforts in Kenyan hospitals.

ETHICS AND DISSEMINATION

The study has been approved by Kenya Medical Research Institute (KEMRI/SERU/CGMR-C/241/4374) and Oxford Tropical Research Ethics Committee (OxTREC 519-22). Research findings will be shared with the sites, and disseminated in seminars, conferences and published in open-access scientific journals.

An observational study of health care provider collaboration networks and heterogenous hospital cost efficiency and quality outcomes

Provider network structure has been linked to hospital cost, utilization, and to a lesser degree quality, outcomes; however, it remains unknown whether these relationships are heterogeneous across different acute care hospital characteristics and US states. The objective of this study is to evaluate whether there are heterogeneous relationships between hospital provider network structure and hospital outcomes (cost efficiency and quality); and to assess the sources of measured heterogeneous effects. We use recent causal random forest techniques to estimate (hospital specific) heterogeneous treatment effects between hospitals' provider network structures and their performance (across cost efficiency and quality). Using Medicare cost report, hospital quality and provider patient sharing data, we study a population of 3061 acute care hospitals in 2016. Our results show that provider networks are significantly associated with costs efficiency (P < .001 for 7/8 network measures), patient rating of their care (P < .1 in 5/8 network measures), heart failure readmissions (P < .01 for 3/8 network measures), and mortality rates (P < .02 in 5/8 cases). We find that fragmented provider structures are associated with higher costs efficiency and patient satisfaction, but also with higher heart failure readmission and mortality rates. These effects are further found to vary systematically with hospital characteristics such as capacity, case mix, ownership, and teaching status. This study used an observational design. In summary, we find that hospital treatment responses to different network structures vary systematically with hospital characteristics..

Medicare accountable care organizations: post-acute care use and post-surgical outcomes in urologic cancer surgery

OBJECTIVES

To evaluate association between Medicare accountable care organizations (ACOs) participation of hospitals on post-acute care (PAC) use and spending, and post-surgical outcomes in Medicare beneficiaries undergoing urologic cancer surgeries. Despite increasing prevalence of urologic cancer and surgical care contributing to a large proportion of total health care costs, and recent Medicare payment reforms such as accountable care organizations, the role of ACOs in urologic cancer care has been unexplored.

METHODS

We conducted a longitudinal analysis of 2011-2017 Medicare claims data to compare post-surgical outcomes between Medicare ACO and non-ACO patients before and after implementation of Medicare shared savings program (MSSP). Our outcomes of interest were Post-acute care (PAC) use (overall, institutional, and home health), Skilled Nursing Facility (SNF) length of stay and Medicare spending for SNF patients, 30-day and 90-day unplanned readmissions and complications after index procedure.

RESULTS

Study sample included a total of 334,514 Medicare patients undergoing bladder, prostate, kidney cancer surgeries at 524 Medicare ACO and 2066 non-ACO hospitals. For bladder cancer surgery, Medicare ACO participation was associated with significantly reduced overall post-acute care use, but not with changes in readmission or complication rate. For prostate cancer and kidney cancer surgery, we found no significant association between hospital participation in Medicare ACOs and PAC use or post-surgical outcomes.

CONCLUSIONS

Hospital participation in MSSP ACOs leads to lower post-acute care use without compromising patient outcomes for Medicare beneficiaries undergoing bladder cancer surgery. Future research is needed to understand longer-term impact of ACO participation on urologic cancer surgery outcomes.

Retrospective observational study of the robustness of provider network structures to the systemic shock of COVID-19: a county level analysis of COVID-19 outcomes

OBJECTIVE

To evaluate whether certain healthcare provider network structures are more robust to systemic shocks such as those presented by the current COVID-19 pandemic.

DESIGN

Using multivariable regression analysis, we measure the effect that provider network structure, derived from Medicare patient sharing data, has on county level COVID-19 outcomes (across mortality and case rates). Our adjusted analysis includes county level socioeconomic and demographic controls, state fixed effects, and uses lagged network measures in order to address concerns of reverse causality.

SETTING

US county level COVID-19 population outcomes by 3 September 2020.

PARTICIPANTS

Healthcare provider patient sharing network statistics were measured at the county level (with n=2541-2573 counties, depending on the network measure used).

PRIMARY AND SECONDARY OUTCOME MEASURES

COVID-19 mortality rate at the population level, COVID-19 mortality rate at the case level and the COVID-19 positive case rate.

RESULTS

We find that provider network structures where primary care physicians (PCPs) are relatively central, or that have greater betweenness or eigenvector centralisation, are associated with lower county level COVID-19 death rates. For the adjusted analysis, our results show that increasing either the relative centrality of PCPs (p value<0.05), or the network centralisation (p value<0.05 or p value<0.01), by 1 SD is associated with a COVID-19 death reduction of 1.0-1.8 per 100 000 individuals (or a death rate reduction of 2.7%-5.0%). We also find some suggestive evidence of an association between provider network structure and COVID-19 case rates.

CONCLUSIONS

Provider network structures with greater relative centrality for PCPs when compared with other providers appear more robust to the systemic shock of COVID-19, as do network structures with greater betweenness and eigenvector centralisation. These findings suggest that how we organise our health systems may affect our ability to respond to systemic shocks such as the COVID-19 pandemic.

Using social network analysis methods to identify networks of physicians responsible for the care of specific patient populations

BACKGROUND

Coordinating health care within and among sectors is crucial to improving quality of care and avoiding undesirable negative health outcomes, such as avoidable hospitalizations. Quality circles are one approach to strengthening collaboration among health care providers and improving the continuity of care. However, identifying and including the right health professionals in such meetings is challenging, especially in settings with no predefined patient pathways. Based on the Accountable Care in Germany (ACD) project, our study presents a framework for and investigates the feasibility of applying social network analysis (SNA) to routine data in order to identify networks of ambulatory physicians who can be considered responsible for the care of specific patients.

METHODS

The ACD study objectives predefined the characteristics of the networks. SNA provides a methodology to identify physicians who have patients in common and ensure that they are involved in health care provision. An expert panel consisting of physicians, health services researchers, and data specialists examined the concept of network construction through informed decisions. The procedure was structured by five steps and was applied to routine data from three German states.

RESULTS

In total, 510 networks of ambulatory physicians met our predefined inclusion criteria. The networks had between 20 and 120 physicians, and 72% included at least ten different medical specialties. Overall, general practitioners accounted for the largest proportion of physicians in the networks (45%), followed by gynecologists (10%), orthopedists, and ophthalmologists (5%). The specialties were distributed similarly across the majority of networks. The number of patients this study allocated to the networks varied between 95 and 45,268 depending on the number and specialization of physicians per network.

CONCLUSIONS

The networks were constructed according to the predefined characteristics following the ACD study objectives, e.g., size of and specialization composition in the networks. This study shows that it is feasible to apply SNA to routine data in order to identify groups of ambulatory physicians who are involved in the treatment of a specific patient population. Whether these doctors are also mainly responsible for care and if their active collaboration can improve the quality of care still needs to be examined.

Provider Network Structure and Black-to-White Disparity Gaps for Medicare Patients with Diabetes: County-Level Analysis of Cost, Utilization, and Clinical Care

BACKGROUND

Prior work has shown that provider network structures correlate with outcomes such as patient costs, utilization, and care. However, it remains unknown whether certain provider networks are associated with reduced disparity gaps.

METHODS

We study the population of Medicare beneficiaries with diabetes who were continuously enrolled in Medicare FFS in 2016. Using multivariable regression analysis of county-level risk adjusted cost, hospitalization, emergency department visits, A1c testing, and preventable diabetes-related hospitalizations, we measure the effect that the relative network connectivity of primary care providers (PCPs) in relation to medical and surgical specialists (PCP/Specialist degree centrality ratio), derived from Medicare patient sharing data, has on non-Hispanic black-to-white disparity gaps controlling for county-level socioeconomic and demographic variables and state fixed effects.

RESULTS

Relative to non-Hispanic white, our adjusted results show that non-Hispanic black beneficiaries have $1673 (p<0.001) higher risk adjusted total costs, 2.6 (p<0.001) more hospitalizations (per 1000 beneficiaries), 11.6 (p<0.001) more ED visits (per 1000 beneficiaries), receive 2.2% (p<0.001) less A1c testing, and have 69.4 (p<0.01) more (per 100,000) avoidable diabetes-related hospital admissions. Our main results show that increasing the PCP/Specialist degree centrality ratio by one standard deviation is associated with a disparity gap decrease of 25.3% (p<0.01) in hospitalizations, 8.3% (p<0.05) in ED visits, 2.8% (p<0.01) in A1c testing, and 26.9% (p<0.1) in the volume of preventable diabetes-related hospital admissions.

CONCLUSIONS

Network structures where PCPs are more central relative to medical and surgical specialists are associated with reduced non-Hispanic black-to-white disparity gaps, suggesting that how we organize and structure our health systems has implications for disparity gaps between non-Hispanic black and white Medicare beneficiaries with diabetes.

Association of Physician Referrals with Timely Cancer Care Using Tumor Registry and Claims Data

More Americans are being screened for and more are surviving colorectal cancer due to advanced treatments and better quality of care; however, these benefits are not equitably distributed among diverse or older populations. Differential care delivery outcomes are driven by multiple factors, including access to timely treatment that comes from high-quality care coordination. Providers help ensure such coordinated care, which includes timely referrals to specialists. Variation in referrals between providers can also result in differences in treatment plans and outcomes. Patients who are more often referred between the same diagnosing and treating providers may benefit from more timely care compared to those who are not. Our objective is to examine patterns of referral, or patient-sharing networks (PSNs), and our outcome, treatment delay of 30-days (yes/no). We hypothesize that if a patient is in a PSN they will have lower odds of a 30-day treatment initiation delay. Our observational population-based analysis using the National Cancer Institute (NCI)-linked tumor registry and Medicare claims database includes records for 27,689 patients diagnosed with colorectal cancer from 2001 to 2013, and treated with either chemotherapy, radiotherapy, or surgery. We modeled the adjusted odds of a delay and found 17.04% of patients experienced a 30-day delay in initial treatment. Factors that increased odds of a delay were lack of membership in a PSN (adjusted odds ratio [AOR]: 2.20; 95% confidence interval [CI]: 1.71-2.84), racial/ethnic minority status, and having multiple comorbidities. Provider characteristics significantly associated with greater odds of a delay were if dyads were not in the same facility (AOR: 1.95; 95% CI: 1.81-2.10), if providers were different genders, most notably male (diagnosing) and female (treating) [AOR: 1.23; 95% CI: 1.08-1.40, p = 0.0015]. PSNs appear to be associated with reduced of a care delay. The associations observed in our study address the demand for developing multilevel interventions to improve the delivery and coordination of high-quality of care for older cancer patients.

Health workers' social networks and their influence in the adoption of strategies to address the stillbirth burden at a subnational level health system in Uganda

Health workers' peer networks are known to influence members' behaviours and practices while translating policies into service delivery. However, little remains known about the extent to which this remains true within interventions aimed at addressing the stillbirth burden in low-resource settings like Uganda. The objective of this study was to examine the health workers' social networks and their influence on the adoption of strategies to address the stillbirth burden at a subnational level health system in Uganda. A qualitative exploratory design was adopted on a purposively selected sample of 16 key informants. The study was conducted in Mukono district among sub-national health systems, managers, health facility in-charges, and frontline health workers. Data was collected using semi-structured interview guides in a face-to-face interview with respondents. The analysis adopted a thematic approach utilising Atlas. ti software for data management. Participants acknowledged that workplace social networks were influential during the implementation of policies to address stillbirth. The influence exerted was in form of linkage with other services, caution, and advice regarding strict adherence to policy recommendations perhaps reflective of the level of trust in providers' ability to adhere to policy provisions. At the district health management level and among non-state actors, support in perceived areas of weak performance in policy implementation was observed. In addition, timely initiation of contact and subsequent referral was another aspect where health workers exerted influence while translating policies to address the stillbirth burden. While the level of support from among network peers was observed to influence health workers' adoption and implementation of strategies to address the stillbirth burden, different mechanisms triggered subsequent response and level of adherence to recommended policy aspects. Drawing from the elicited responses, we infer that health workers' social networks influence the direction and extent of success in policy implementation to address the stillbirth burden at the subnational level.

Physician Network Connections Associated With Faster De-Adoption of Dronedarone for Permanent Atrial Fibrillation

BACKGROUND

Physicians' professional networks are an important source of new medical information and have been shown to influence the adoption of new treatments, but it is unknown how physician networks impact the de-adoption of harmful practices.

METHODS

We analyzed changes in physicians' use of dronedarone after the PALLAS trial (Palbociclib Collaborative Adjuvant Study; November 2011) showed that dronedarone increased the risk of death from cardiovascular events among patients with permanent atrial fibrillation. Deidentified administrative claims from the OptumLabs Data Warehouse were combined with physicians' demographic information from the Doximity database and publicly available data on physicians' patient-sharing relationships compiled by the Centers for Medicare and Medicaid Services. We used a linear probability model with an interrupted linear time trend specification to model the impact of the PALLAS trial on physicians' dronedarone usage between 2009 and 2014.

RESULTS

Before the PALLAS trial, the use of dronedarone was increasing by 0.22 percentage points per quarter (95% CI, 0.19-0.25) in our Medicare Advantage sample (N=343 429 patient-quarter observations) and 0.63 percentage points per quarter (95% CI, 0.52-0.75) in our commercially insured sample (N=44 402 patient-quarter observations). After the PALLAS trial and subsequent United States Food and Drug Administration black box warning, physicians in the Medicare Advantage sample with an above-median number of network connections to other physicians decreased their quarterly usage of dronedarone by 0.12 percentage points more per quarter (95% CI, -0.20 to -0.04; P=0.031) than physicians with equal to or below the median number of network connections. Similar patterns existed in the commercially insured sample (P=0.0318).

CONCLUSIONS

After controlling for a wide range of patient, physician, and geographic characteristics, physicians with a greater number of network connections were faster de-adopters of dronedarone for patients with permanent atrial fibrillation after the PALLAS trial and subsequent United States Food and Drug Administration black box warning detailed the harmfulness of dronedarone for these patients. Policies for improving physicians' responsiveness to new medical information should consider utilizing the influence of these important professional network relationships.

Tie Decay and Dissolution: Contentious Prescribing Practices in the Prescription Drug Epidemic

Although a substantial body of work has investigated drivers of tie formation, there is growing interest in understanding why relationships decay or dissolve altogether. The networks literature has tended to conceptualize tie decay as driven by processes similar to those underlying tie formation. Yet information that is revealed through ongoing interactions can exert different effects on tie formation and tie decay. This paper investigates how tie decay and tie formation processes differ by focusing on contentious practices. To the extent that information about dissimilarities in contentious practices is learned through ongoing interactions, it can exert diverging effects on tie formation and tie decay. Using a longitudinal data set of 141,543 physician dyads, we find that differences in contentious prescribing led ties to weaken or dissolve altogether but did not affect tie formation. The more contentious the practice and the more information available about the practice, the stronger the effect on tie decay and dissolution. Collectively, these findings contribute to a more nuanced understanding of relationship evolution as an unfolding process through which deeper-level differences are revealed and shape the outcome of the tie.

Physician network connections to specialists and HIV quality of care

OBJECTIVE

To estimate novel measures of generalist physicians' network connectedness to HIV specialists and their associations with two dimensions of HIV quality of care.

DATA SOURCES

Medicare and Medicaid claims and the American Medical Association Masterfile data on people living with HIV (PLWH) and the physicians providing their HIV care in California between 2007 and 2010.

STUDY DESIGN

I construct regional patient-sharing physician networks from the shared treatment of PLWH and calculate (a) measures of network connectedness to all physician types and (b) specialty-weighted measures to describe connectedness to HIV specialists. Two HIV quality of care outcomes are then evaluated: medication quality (prescribing antiretroviral drugs from at least two drug classes) and monitoring quality (at least two annual HIV virus monitoring scans). Linear probability models estimate the associations between network statistics and the two dimensions of HIV quality of care, and a policy simulation demonstrates the importance of these statistical relationships. These analyses include 16 124 PLWH, 3240 generalists, and 1031 HIV specialists.

DATA COLLECTION/EXTRACTION METHODS

PLWH are identified from claims for patients with any indication of HIV using an existing algorithm from the literature.

PRINCIPAL FINDINGS

Generalists' network connectedness to HIV specialists is positively related with their own HIV medication quality; one additional HIV specialist connection is associated with a 1.46 percentage point (SE 0.42, P < .01) increase in generalist's medication quality. Based on the estimated associations, a simulated policy that increases connectedness between generalists and HIV specialists reduces the annual rate of HIV infections by up to 6%, roughly 290 fewer infections per year. Only network connectedness to all physician types is associated with improved monitoring quality.

CONCLUSIONS

Network connectedness to HIV specialists is positively associated with generalists' HIV medication quality, which suggests that specialists provide clinical support through patient-sharing for complex treatment protocol.

Physician networks and potentially inappropriate opioid prescriptions

Background: Opioid overdose is a national health priority and curbing inappropriate prescribing is critical. In 2016, the Centers for Disease Control and Prevention (CDC) issued appropriate prescribing guidelines.Objectives: Examine associations between care networks defined by shared patients and problematic opioid prescribing.Methods: Analysis was at the provider-year level. Social network analysis (SNA) applied to the Medicaid MarketScan^® Research Database for the years 2010-2015 identified care communities, each community's level of integration (centralization), and each provider's integration (centrality). Nested multivariable logistic regressions controlling for patient mix and provider specialty simultaneously examined the risk of any (incident) and repeated (prevalent) inappropriate prescribing.Outcomes: Four behaviors defined by the CDC guidelines were examined: (1) more than 90 days continuous supply of high-dose opioid analgesics for chronic pain, (2) overlapping opioid supplies, (3) overlapping opioid and benzodiazepine prescriptions, and (4) prescribing an extended release opioid for an acute pain diagnosis.Results: Provider centrality was associated with reduced incidence of outcome (2) (OR: 0.95) and decreased prevalence of outcomes (1), (2), and (3). However, higher incidence (OR: 1.32) and prevalence (OR: 1.027) of outcome (4) were observed. Conversely, centralization associated with decreased incidence of (1) and (2) and lower prevalence of (1), (2), and (3).Conclusions: Greater provider integration is associated with a lower risk of a provider's patients repeatedly having potentially inappropriate prescription fills; however, the association with a provider having any potentially problematic prescription is more ambiguous.

Promoting rational antibiotic prescribing for non-complicated infections: understanding social influence in primary care networks in Germany

Background

Primary care networks in Germany are formalized regional collaborations of physicians and other healthcare providers. Common goals are optimized healthcare processes and services for patients, enhanced communication, agency for professional concerns and strengthened economic power. In the ARena study (Sustainable reduction of antibiotic-induced antimicrobial resistance), 14 primary care networks in two federal German states aimed to promote appropriate antibiotics use for acute non-complicated infections by fostering awareness and understanding. Factors related to the role of primary care networks were to be identified.

Methods

For this study, audio-recorded telephone interviews were conducted with physicians, non-physician health professionals and stakeholder representatives. Pseudonymized verbatim transcripts were coded using thematic analysis. In-depth analysis was based on the inductive categories ‘social support’, ‘social learning’, ‘social normative pressures’ and ‘social contagion’ to reflect social influence processes. Data generated through a survey with physicians and non-physician health professionals were analyzed descriptively to foster understanding of the networks’ potential impact on antibiotic prescribing.

Results

Social influence processes proved to be relevant regarding knowledge transfer, manifestation of best-practice care and self-reflection. Peer communication was seen as a great asset, the main reason for membership and affirmative for own perspectives. All interviewed physicians (n = 27) considered their network to be a strong support factor for daily routines, introduction of new routines, and continuity of care. They utilized network-offered training programs focusing on best practice guideline-oriented use of antibiotics and considered their networks supportive in dealing with patient expectations. A shared attitude combined with ARena intervention components facilitated reflective management of antibiotic prescribing. Non-physician health professionals (n = 11) also valued network peer exchange. They assumed their employers joined networks to offer improved and continuous care. Stakeholders (n = 7) expected networks and their members to be drivers for care optimization.

Conclusion

Primary care networks play a crucial role in providing a platform for professional peer exchange, social support and reassurance. With regards to their impact on antibiotic prescribing for acute non-complicated infections, networks seem to facilitate and amplify quality improvement programs by providing a platform for refreshing awareness, knowledge and self-reflection among care providers. They are well suited to promote a rational use of antibiotics.

Trial registration

ISRCTN, ISRCTN58150046. Registered 24 August 2017.

Use of Medicare Data to Identify Team-based Primary Care: Is it Possible?

BACKGROUND

It is unclear whether Medicare data can be used to identify type and degree of collaboration between primary care providers (PCPs) [medical doctors (MDs), nurse practitioners, and physician assistants] in a team care model.

METHODS

We surveyed 63 primary care practices in Texas and linked the survey results to 2015 100% Medicare data. We identified PCP dyads of 2 providers in Medicare data and compared the results to those from our survey. Sensitivity, specificity, and positive predictive value (PPV) of dyads in Medicare data at different threshold numbers of shared patients were reported. We also identified PCPs who work in the same practice by Social Network Analysis (SNA) of Medicare data and compared the results to the surveys.

RESULTS

With a cutoff of sharing at least 30 patients, the sensitivity of identifying dyads was 27.8%, specificity was 91.7%, and PPV 72.2%. The PPV was higher for MD-nurse practitioner/physician assistant pairs (84.4%) than for MD-MD pairs (61.5%). At the same cutoff, 90% of PCPs identified in a practice from the survey were also identified by SNA in the corresponding practice. In 5 of 8 surveyed practices with at least 3 PCPs, about ≤20% PCPs identified in the practices by SNA of Medicare data were not identified in the survey.

CONCLUSIONS

Medicare data can be used to identify shared care with low sensitivity and high PPV. Community discovery from Medicare data provided good agreement in identifying members of practices. Adapting network analyses in different contexts needs more validation studies.

Receipt of Promotional Payments at the Individual and Physician Network Level Associated with Higher Branded Antipsychotic Prescribing Rates

Pharmaceutical promotion can lead to market size expansion, which is beneficial if previously untreated patients access treatment but deleterious if it leads to overuse, an area of concern for second generation antipsychotics (SGA). We contribute to a growing body of work suggesting that networks of social and professional relationships shape prescribing behavior. We examined 88,439 Medicare Part D prescribing physicians, finding that promotion is associated with SGA market size expansion (elasticity: 0.062) and that network-level promotional activity is associated with network members' branded product prescribing. Research on the effects of promotion should account for its effects in prescribers' networks.

The formation of physician patient sharing networks in medicare: Exploring the effect of hospital affiliation

This study explores the forces that drive the formation of physician patient sharing networks. In particular, I examine the degree to which hospital affiliation drives physicians' sharing of Medicare patients. Using a revealed preference framework where observed network links are taken to be pairwise stable, I estimate the physicians' pair-specific values using a tetrad maximum score estimator that is robust to the presence of unobserved physician specific characteristics. I also control for a number of potentially confounding patient sharing channels, such as (a) common physician group or hospital system affiliation, (b) physician homophily, (c) knowledge complementarity, (d) patient side considerations related to both geographic proximity and insurance network participation, and (e) spillover from other collaborations. Focusing on the Chicago hospital referral region, I find that shared hospital affiliation accounts for 36.5% of the average pair-specific utility from a link. Implications for reducing care fragmentation are discussed.

Network analysis of medical care services

Medical care services can be organized into a network. Understanding the structure of this network cannot only help analyze common clinical protocols but can also help reveal previously unknown patterns of care. The objective of this research is to introduce the concept and methods for constructing and analyzing the network of medical care services. We start by demonstrating how to build the network itself and then develop algorithms, based on principal component analysis and social network analysis, to detect communities of services. Finally, we propose novel graphical techniques for representing and assessing patterns of care. We demonstrate the application of our algorithms using data from an Emergency Department in New York State. One of the implications of our research is that clinical experts could use our algorithms to detect deviations from either existing protocols of care or administrative norms.

Association Between Degrees of Separation in Physician Networks and Surgeons' Use of Perioperative Breast Magnetic Resonance Imaging

BACKGROUND

Perioperative magnetic resonance imaging (MRI) is frequently used in breast cancer despite unproven benefits. It is unclear whether surgeons' use of breast MRI is associated with the practices of other surgeons to whom they are connected through shared patients.

METHODS

We conducted a retrospective study using Medicare data to identify physicians providing breast cancer care during 2007-2009 and grouped them into patient-sharing networks. Physician pairs were classified according to their "degree of separation" based on patient-sharing (eg, physician pairs that care for the same patients were separated by 1 degree; pairs that both share patients with another physician but not with each other were separated by 2 degrees). We assessed the association between the MRI use of a surgeon and the practice patterns of surgical colleagues by comparing MRI use in the observed networks with networks with randomly shuffled rates of MRI utilization.

RESULTS

Of the 15,273 patients who underwent surgery during the study period, 28.8% received perioperative MRI. These patients received care from 1806 surgeons in 60 patient-sharing networks; 55.1% of surgeons used MRI. A surgeon was 24.5% more likely to use MRI if they were directly connected to a surgeon who used MRI. This effect decreased to 16.3% for pairs of surgeons separated by 2 degrees, and 0.8% at the third degree of separation.

CONCLUSIONS

Surgeons' use of perioperative breast MRI is associated with the practice of surgeons connected to them through patient-sharing; the strength of this association attenuates as the degree of separation increases.

Why Health Care Professionals Belong to an Intensive Care Virtual Community: Qualitative Study

Background

Clinical practice variation that results in poor patient outcomes remains a pressing problem for health care organizations. Some evidence suggests that a key factor may be ineffective internal and professional networks that limit knowledge exchange among health care professionals. Virtual communities have the potential to overcome professional and organizational barriers and facilitate knowledge flow.

Objective

This study aimed to explore why health care professionals belong to an exemplar virtual community, ICUConnect. The specific research objectives were to (1) understand why members join a virtual community and remain a member, (2) identify what purpose the virtual community serves in their professional lives, (3) identify how a member uses the virtual community, and (4) identify how members used the knowledge or resources shared on the virtual community.

Methods

A qualitative design, underpinned by pragmatism, was used to collect data from 3 asynchronous online focus groups and 4 key informant interviews, with participants allocated to a group based on their posting behaviors during the previous two years—between September 1, 2012, and August 31, 2014: (1) frequent (>5 times), (2) low (≤5 times), and (3) nonposters. A novel approach to focus group moderation, based on the principles of traditional focus groups, and e-moderating was developed. Thematic analysis was undertaken, applying the Diffusion of Innovation theory as the theoretical lens. NCapture (QRS International) was used to extract data from the focus groups, and NVivo was used to manage all data. A research diary and audit trail were maintained.

Results

There were 27 participants: 7 frequent posters, 13 low posters, and 7 nonposters. All participants displayed an external orientation, with the majority using other social media; however, listservs were perceived to be superior in terms of professional compatibility and complexity. The main theme was as follows: “Intensive care professionals are members of ICUConnect because by being a member of a broader community they have access to credible best-practice knowledge.” The virtual community facilitated access to all professionals caring for the critically ill and was characterized by a positive and collegial online culture. The knowledge found was credible because it was extensive and because the virtual community was moderated and sponsored by a government agency. This enabled members to benchmark and improve their unit practices and keep up to date.

Conclusions

This group of health care professionals made a strategic decision to be members of ICUConnect, as they understood that to provide up-to-date clinical practices, they needed to network with colleagues in other facilities. This demonstrated that a closed specialty-specific virtual community can create a broad heterogeneous professional network, overcoming current ineffective networks that may adversely impact knowledge exchange and creation in local practice settings. To address clinical practice variation, health care organizations can leverage low-cost social media technologies to improve interprofessional and interorganizational networks.

Impact of care provider network characteristics on patient outcomes: Usage of social network analysis and a multi-scale community detection

Objective

We assess healthcare provider collaboration and the impact on patient outcomes using social network analysis, a multi-scale community detection algorithm, and generalized estimating equations.

Material and methods

A longitudinal analysis of health claims data of a large employer over a 3 year period was performed to measure how provider relationships impact patient outcomes. The study cohort included 4,230 patients with 167 providers. Social network analysis with a multi-scale community detection algorithm was used to identify groups of healthcare providers more closely working together. Resulting measures of provider collaboration were: 1) degree, 2) betweenness, and 3) closeness centrality. The three patient outcome measures were 1) emergency department visit, 2) inpatient hospitalization, and 3) unplanned hospitalization. Relationships between provider collaboration and patient outcomes were assessed using generalized estimating equations. General practitioner, family practice, and internal medicine were labeled as primary care. Cardiovascular, endocrinologists, etc. were labeled as specialists, and providers such as radiology and social workers were labeled as others.

Results

Higher connectedness (degree) and higher access (closeness) to other providers in the community were significant for reducing inpatient hospitalization and emergency department visits. Patients of specialists (e.g. cardiovascular) and providers specified as others (e.g. social worker) had higher rate of hospitalization and emergency department visits compared to patients of primary care providers.

Conclusion

Application of social network analysis for developing healthcare provider networks can be leveraged by community detection algorithms and predictive modeling to identify providers’ network characteristics and their impacts on patient outcomes. The proposed framework presents multi-scale measures to assess characteristics of healthcare providers and their impact on patient outcomes. This approach can be used by implementation experts for informed decision-making regarding the design of insurance coverage plans, and wellness promotion programs. Health services researchers can use the study approach for assessment of provider collaboration and impacts on patient outcomes.

Surgeon peer network characteristics and adoption of new imaging techniques in breast cancer: A study of perioperative MRI

Background

Perioperative MRI has disseminated into breast cancer practice despite equivocal evidence. We used a novel social network approach to assess the relationship between the characteristics of surgeons’ patient‐sharing networks and subsequent use of MRI.

Methods

We identified a cohort of female patients with stage 0‐III breast cancer from the Surveillance, Epidemiology, and End Results (SEER)‐Medicare database. We used claims data from these patients and non‐cancer patients from the 5% Medicare sample to identify peer groups of physicians who shared patients during 2004‐2006 (T1). We used a multivariable hierarchical model to identify peer group characteristics associated with uptake of MRI in T2 (2007‐2009) by surgeons who had not used MRI in T1.

Results

Our T1 sample included 15 149 patients with breast cancer, treated by 2439 surgeons in 390 physician groups. During T1, 9.1% of patients received an MRI; the use of MRI varied from 0% to 100% (IQR 0%, 8.5%) across peer groups. After adjusting for clinical characteristics, patients treated by surgeons in groups with a higher proportion of primary care physicians (PCPs) in T1 were less likely to receive MRI in T2 (OR = 0.81 for 10% increase in PCPs, 95% CI = 0.71, 0.93). Surgeon transitivity (ie, clustering of surgeons) was significantly associated with MRI receipt (P = 0.013); patients whose surgeons were in groups with higher transitivity in T1 were more likely to receive MRI in T2 (OR = 1.29 for 10% increase in clustering, 95% CI = 1.06, 1.58).

Conclusion

The characteristics of a surgeon's peer network are associated with their patients’ subsequent receipt of perioperative MRI.

A scoping review of patient-sharing network studies using administrative data

There is a robust literature examining social networks and health, which draws on the network traditions in sociology and statistics. However, the application of social network approaches to understand the organization of health care is less well understood. The objective of this work was to examine approaches to conceptualizing, measuring, and analyzing provider patient-sharing networks. These networks are constructed using administrative data in which pairs of physicians are considered connected if they both deliver care to the same patient. A scoping review of English language peer-reviewed articles in PubMed and Embase was conducted from inception to June 2017. Two reviewers evaluated article eligibility based upon inclusion criteria and abstracted relevant data into a database. The literature search identified 10,855 titles, of which 63 full-text articles were examined. Nine additional papers identified by reviewing article references and authors were examined. Of the 49 papers that met criteria for study inclusion, 39 used a cross-sectional study design, 6 used a cohort design, and 4 were longitudinal. We found that studies most commonly theorized that networks reflected aspects of collaboration or coordination. Less commonly, studies drew on the strength of weak ties or diffusion of innovation frameworks. A total of 180 social network measures were used to describe the networks of individual providers, provider pairs and triads, the network as a whole, and patients. The literature on patient-sharing relationships between providers is marked by a diversity of measures and approaches. We highlight key considerations in network identification including the definition of network ties, setting geographic boundaries, and identifying clusters of providers, and discuss gaps for future study.

Behavioral Health's Integration Within a Care Network and Health Care Utilization

OBJECTIVE

Examine how behavioral health (BH) integration affects health care costs, emergency department (ED) visits, and inpatient admissions.

DATA SOURCES/STUDY SETTING

Truven Health MarketScan Research Databases.

STUDY DESIGN

Social network analysis identified "care communities" (providers sharing a high number of patients) and measured BH integration in terms of how connected, or central, BH providers were to other providers in their community. Multivariable generalized linear models adjusting for age, sex, number of prescriptions, and Charlson comorbidity score were used to estimate the relationship between the centrality of BH providers and health care utilization of BH patients.

DATA COLLECTION/EXTRACTION METHODS

Used outpatient, inpatient, and pharmacy claims data from six Medicaid plans from 2011 to 2013 to identify study outcomes, comorbidities, providers, and health care encounters.

PRINCIPAL FINDINGS

Behavioral health centrality ranged from 0 (no BH providers) to 0.49. Relative to communities at the median BH centrality (0.06), in 2012, BH patients in communities at the 75th percentile of BH centrality (0.31) had 0.2 fewer admissions, 2.1 fewer all-cause ED visits, and accrued $1,947 fewer costs, on average.

CONCLUSIONS

Increased behavioral centrality was significantly associated with a reduced number of ED visits, less frequent inpatient admissions, and lower overall health care costs.

The Role of Organizational Affiliations in Physician Patient-Sharing Relationships

Provider consolidation may enable improved care coordination, but raises concerns about lack of competition. Physician patient-sharing relationships play a key role in constructing patient care teams, but it is unknown how organization affiliations affect these. We use the Massachusetts All Payer Claims Database to examine whether patient-sharing relationships are associated with sharing a practice site, medical group, and/or physician contracting network. Physicians were 17 percentage points more likely to have a patient-sharing relationship if they shared a practice site and 4 percentage points more likely if they shared a medical group, as compared with sharing no affiliation. However, there was no detectable increased probability of a patient-sharing relationship within the same physician contracting network. Our finding that physician patient-sharing relationships are concentrated within organizational boundaries at practice site and medical group levels helps illuminate referral incentives and provide insight into the role of organizational affiliations in patient care team construction.

Applications of network analysis to routinely collected health care data: a systematic review

Objective

To survey network analyses of datasets collected in the course of routine operations in health care settings and identify driving questions, methods, needs, and potential for future research.

Materials and Methods

A search strategy was designed to find studies that applied network analysis to routinely collected health care datasets and was adapted to 3 bibliographic databases. The results were grouped according to a thematic analysis of their settings, objectives, data, and methods. Each group received a methodological synthesis.

Results

The search found 189 distinct studies reported before August 2016. We manually partitioned the sample into 4 groups, which investigated institutional exchange, physician collaboration, clinical co-occurrence, and workplace interaction networks. Several robust and ongoing research programs were discerned within (and sometimes across) the groups. Little interaction was observed between these programs, despite conceptual and methodological similarities.

Discussion

We use the literature sample to inform a discussion of good practice at this methodological interface, including the concordance of motivations, study design, data, and tools and the validation and standardization of techniques. We then highlight instances of positive feedback between methodological development and knowledge domains and assess the overall cohesion of the sample.

Creating a National Provider Identifier (NPI) to Unique Physician Identification Number (UPIN) Crosswalk for Medicare Data

INTRODUCTION

Many health services researchers are interested in assessing long term, individual physician treatment patterns, particularly for cancer care. In 2007, Medicare changed the physician identifier used on billed services from the Unique Physician Identification Number (UPIN) to the National Provider Identifier (NPI), precluding the ability to use Medicare claims data to evaluate individual physician treatment patterns across this transition period.

METHODS

Using the 2007-2008 carrier (physician) claims from the linked Surveillance, Epidemiology and End Results (SEER) cancer registry-Medicare data and Medicare's NPI and UPIN Directories, we created a crosswalk that paired physician NPIs included in SEER-Medicare data with UPINs. We evaluated the ability to identify an NPI-UPIN match by physician sex and specialty.

RESULTS

We identified 470,313 unique NPIs in the 2007-2008 SEER-Medicare carrier claims and found a UPIN match for 90.1% of these NPIs (n=423,842) based on 3 approaches: (1) NPI and UPIN coreported on the SEER-Medicare claims; (2) UPINs reported on the NPI Directory; or (3) a name match between the NPI and UPIN Directories. A total of 46.6% (n=219,315) of NPIs matched to the same UPIN across all 3 approaches, 34.1% (n=160,277) agreed across 2 approaches, and 9.4% (n=44,250) had a match identified by 1 approach only. NPIs were paired to UPINs less frequently for women and primary care physicians compared with other specialists.

DISCUSSION

National Cancer Institute has created a crosswalk resource available to researchers that links NPIs and UPINs based on the SEER-Medicare data. In addition, the documented process could be used to create other NPI-UPIN crosswalks using data beyond SEER-Medicare.

The Impact of Social Contagion on Physician Adoption of Advanced Imaging Tests in Breast Cancer

Background

Magnetic resonance imaging (MRI) and positron emission tomography (PET) scans are widely used in breast cancer practice despite unproven benefits. We examined the extent to which social contagion is associated with adoption of these imaging modalities.

Methods

We used Surveillance, Epidemiology, and End Results-Medicare to construct peer groups of physicians who shared patients during a baseline period when these imaging modalities were starting to disseminate into practice (2004-2006) and determined the potential impact of these peer groups during a follow-up period (2007-2009). For non-early-adopting surgeons (whose patients did not receive MRI/PET during baseline), we used hierarchical logistic regression models to examine the effect of their peer group's baseline use on their use of MRI/PET during the follow-up period, adjusting for patient characteristics and hospital MRI/PET use.

Results

For MRI, there were 6424 women diagnosed in the follow-up period assigned to 986 non-early-adopting surgeons. During baseline, 9.3% of women received an MRI, varying across peer groups from 0% to 81%. Women assigned to surgeons whose peers had the highest rate of baseline MRI use were more likely to receive MRI compared with women whose surgeons' peers did not use MRI (24.9% vs 10.1%, adjusted odds ratio [OR] = 2.47, 95% confidence interval [CI] = 1.39 to 4.39). Physician peers were associated with uptake of PET imaging (OR for highest vs lowest baseline peer group PET use = 2.04, 95% CI = 1.24 to 3.36).

Conclusions

The phenomenon of social contagion may offer opportunities to better understand how new approaches to cancer care disseminate into clinical practice.

Repeated, Close Physician Coronary Artery Bypass Grafting Teams Associated with Greater Teamwork

OBJECTIVE

To determine whether observed patterns of physician interaction around shared patients are associated with higher levels of teamwork as perceived by physicians.

DATA SOURCES/STUDY SETTING

Michigan Medicare beneficiaries who underwent coronary artery bypass grafting (CABG) procedures at 24 hospitals in the state between 2008 and 2011.

STUDY DESIGN

We assessed hospital teamwork using the teamwork climate scale in the Safety Attitudes Questionnaire. After aggregating across CABG discharges at these hospitals, we mapped the physician referral networks (including both surgeons and nonsurgeons) that served them and measured three network properties: (1) reinforcement, (2) clustering, and (3) density. We then used multilevel regression models to identify associations between network properties and teamwork at the hospitals on which the networks were anchored.

PRINCIPAL FINDINGS

In hospitals where physicians repeatedly cared for patients with the same colleagues, physicians perceived better teamwork (β-reinforcement = 3.28, p = .003). When physicians who worked together also had other colleagues in common, the reported teamwork was stronger (β clustering = 1.71, p = .001). Reported teamwork did not change when physicians worked with a higher proportion of other physicians at the hospital (β density = -0.58, p = .64).

CONCLUSION

In networks with higher levels of reinforcement and clustering, physicians perceive stronger teamwork, perhaps because the strong ties between them create a shared understanding; however, sharing patients with more physicians overall (i.e., density) did not lead to stronger teamwork. Clinical and organizational leaders may consider designing the structure of clinical teams to increase interactions with known colleagues and repeated interactions between providers.

Properties of healthcare teaming networks as a function of network construction algorithms

Network models of healthcare systems can be used to examine how providers collaborate, communicate, refer patients to each other, and to map how patients traverse the network of providers. Most healthcare service network models have been constructed from patient claims data, using billing claims to link a patient with a specific provider in time. The data sets can be quite large (106-108 individual claims per year), making standard methods for network construction computationally challenging and thus requiring the use of alternate construction algorithms. While these alternate methods have seen increasing use in generating healthcare networks, there is little to no literature comparing the differences in the structural properties of the generated networks, which as we demonstrate, can be dramatically different. To address this issue, we compared the properties of healthcare networks constructed using different algorithms from 2013 Medicare Part B outpatient claims data. Three different algorithms were compared: binning, sliding frame, and trace-route. Unipartite networks linking either providers or healthcare organizations by shared patients were built using each method. We find that each algorithm produced networks with substantially different topological properties, as reflected by numbers of edges, network density, assortativity, clustering coefficients and other structural measures. Provider networks adhered to a power law, while organization networks were best fit by a power law with exponential cutoff. Censoring networks to exclude edges with less than 11 shared patients, a common de-identification practice for healthcare network data, markedly reduced edge numbers and network density, and greatly altered measures of vertex prominence such as the betweenness centrality. Data analysis identified patterns in the distance patients travel between network providers, and a striking set of teaming relationships between providers in the Northeast United States and Florida, likely due to seasonal residence patterns of Medicare beneficiaries. We conclude that the choice of network construction algorithm is critical for healthcare network analysis, and discuss the implications of our findings for selecting the algorithm best suited to the type of analysis to be performed.

Geographic Variations in Physician Relationships Over Time: Implications for Care Coordination

Care coordination may be more challenging when the specific physicians with whom primary care physicians (PCPs) are expected to coordinate care change over time. Using Medicare data on physician patient-sharing relationships and the Dartmouth Atlas, we explored the extent to which PCPs tend to share patients with other physicians over time. We found that 70.7% of ties between PCPs and other physicians that were present in 2012 persisted in 2013, and additional shared patients in 2012 increased the odds of being connected in 2013. Regions with higher persistent ties tended to have lower rates of emergency room visits, and regions where PCPs had more physician connections were more likely to have higher emergency room visits. The results point to potential opportunities and challenges faced by health care reforms that seek to improve coordination.

Association Between Physician Teamwork and Health System Outcomes After Coronary Artery Bypass Grafting

BACKGROUND

Patients undergoing coronary artery bypass grafting (CABG) must often see multiple providers dispersed across many care locations. To test whether teamwork (assessed with the bipartite clustering coefficient) among these physicians is a determinant of surgical outcomes, we examined national Medicare data from patients undergoing CABG.

METHODS AND RESULTS

Among Medicare beneficiaries who underwent CABG between 2008 and 2011, we mapped relationships between all physicians who treated them during their surgical episodes, including both surgeons and nonsurgeons. After aggregating across CABG episodes in a year to construct the physician social networks serving each health system, we then assessed the level of physician teamwork in these networks with the bipartite clustering coefficient. Finally, we fit a series of multivariable regression models to evaluate associations between a health system's teamwork level and its 60-day surgical outcomes. We observed substantial variation in the level of teamwork between health systems performing CABG (SD for the bipartite clustering coefficient was 0.09). Although health systems with high and low teamwork levels treated beneficiaries with comparable comorbidity scores, these health systems differed over several sociocultural and healthcare capacity factors (eg, physician staff size and surgical caseload). After controlling for these differences, health systems with higher teamwork levels had significantly lower 60-day rates of emergency department visit, readmission, and mortality.

CONCLUSIONS

Health systems with physicians who tend to work together in tightly-knit groups during CABG episodes realize better surgical outcomes. As such, delivery system reforms focused on building teamwork may have positive effects on surgical care.

Comparison of Comorbidity Scores in Predicting Surgical Outcomes

INTRODUCTION

The optimal methodology for assessing comorbidity to predict various surgical outcomes such as mortality, readmissions, complications, and failure to rescue (FTR) using claims data has not been established.

OBJECTIVE

Compare diagnosis-based and prescription-based comorbidity scores for predicting surgical outcomes.

METHODS

We used 100% Texas Medicare data (2006-2011) and included patients undergoing coronary artery bypass grafting, pulmonary lobectomy, endovascular repair of abdominal aortic aneurysm, open repair of abdominal aortic aneurysm, colectomy, and hip replacement (N=39,616). The ability of diagnosis-based [Charlson comorbidity score, Elixhauser comorbidity score, Combined Comorbidity Score, Centers for Medicare and Medicaid Services-Hierarchical Condition Categories (CMS-HCC)] versus prescription-based Chronic disease score in predicting 30-day mortality, 1-year mortality, 30-day readmission, complications, and FTR were compared using c-statistics (c) and integrated discrimination improvement (IDI).

RESULTS

The overall 30-day mortality was 5.8%, 1-year mortality was 17.7%, 30-day readmission was 14.1%, complication rate was 39.7%, and FTR was 14.5%. CMS-HCC performed the best in predicting surgical outcomes (30-d mortality, c=0.797, IDI=4.59%; 1-y mortality, c=0.798, IDI=9.60%; 30-d readmission, c=0.630, IDI=1.27%; complications, c=0.766, IDI=9.37%; FTR, c=0.811, IDI=5.24%) followed by Elixhauser comorbidity index/disease categories (30-d mortality, c=0.750, IDI=2.37%; 1-y mortality, c=0.755, IDI=5.82%; 30-d readmission, c=0.629, IDI=1.43%; complications, c=0.730, IDI=3.99%; FTR, c=0.749, IDI=2.17%). Addition of prescription-based scores to diagnosis-based scores did not improve performance.

CONCLUSIONS

The CMS-HCC had superior performance in predicting surgical outcomes. Prescription-based scores, alone or in addition to diagnosis-based scores, were not better than any diagnosis-based scoring system.

Physician's peer exposure and the adoption of a new cancer treatment modality

BACKGROUND

New technologies, often with limited evidence to support their effectiveness, frequently diffuse into clinical practice and increase the costs of cancer care. The authors studied whether physician peer exposure was associated with the subsequent adoption of a new approach to adjuvant radiotherapy (brachytherapy) for the treatment of women with early-stage breast cancer.

METHODS

A retrospective cohort study was performed using Surveillance, Epidemiology, and End Results (SEER)-Medicare data. Data from 2003 through 2004 were used to classify surgeons as early brachytherapy adopters and, among non-early adopters, whether they shared patients with early adopters (peer exposure). Data from 2005 through 2006 were used to examine whether women were more likely to receive brachytherapy if their surgeons were exposed to early adopters.

RESULTS

Overall, the percentage of women receiving brachytherapy increased from 3.2% in 2003 through 2004 to 4.7% in 2005 through 2006. In this latter period, a total of 2087 patients were assigned to 328 non-early adopting surgeons. In unadjusted analyses, patients whose surgeons were connected to early adopters during 2003 through 2004 were found to be significantly more likely to receive brachytherapy in 2005 through 2006 compared with those whose surgeons were not connected to early adopters (8.0% vs 4.1%; P = .003). In adjusted analyses, the predicted probability of receiving brachytherapy among patients whose surgeon did have an early-adopting peer was 3.9% versus 1.0% among those whose surgeons did not have an early-adopting peer (P = .03).

CONCLUSIONS

Exposure to peers who were early adopters of brachytherapy was found to be associated with a surgeon's subsequent uptake of brachytherapy. The results of the current study provide an example of a novel approach to examining the diffusion of innovation in cancer care.