The Demographics of Menière's Disease: Selection Bias or Differential Susceptibility?

OBJECTIVE: To clarify whether the reported lack of racial and ethnic diversity among Menière's disease (MD) patients is representative of selection bias or disease susceptibility. STUDY DESIGN: Retrospective medical record review and population-level analyses. SETTING: Tertiary referral center. PATIENTS: Cohort of 1091 patients diagnosed with MD by the tertiary otology service. MAIN OUTCOME MEASURE: Demographic and population-level characteristics (age, sex, race, insurance status, ZIP code, median income, education level) compared with local, regional, health system, and otolaryngology clinic demographics. RESULTS: Patients seen for MD were significantly older than those seen throughout the otolaryngology clinic (median, 65.0 versus 58.8 yr) or health system (65.0 versus 50.8 yr). A majority of patients with MD were of White race (92%), compared with 2.7% Black race and 0.5% Asian. Using population-level data, median income and having medical insurance were significantly correlated with care for MD. A disproportionate rate of care for MD was seen in ZIP codes outside urban areas as compared with other otologic and otolaryngologic conditions seen in the same clinic. CONCLUSION: Patients with MD are of older age, more likely to be of White race, and disproportionately from rural locales. The demographic profile of patients diagnosed with MD by tertiary otology is better explained by differential susceptibility to MD than by selection bias.

Association between body-mass index, patient characteristics, and obesity-related comorbidities among COVID-19 patients: A prospective cohort study.

OBJECTIVE: Obesity is a major risk factor for adverse outcomes after COVID-19 infection. However, it is unknown if the worse outcomes are due to the confounding effect of demographic and obesity-related comorbidities. The study objective is to analyze associations between body mass index, patient characteristics, obesity-related comorbidity, and clinical outcomes in COVID-19 patients. METHODS: In this prospective cohort study, we chose patient records between March 1st, 2020, and December 1st, 2022, in a large tertiary care center in southeast Wisconsin in the United States. Patients over the age of 18 who tested positive were included in the study. Clinical outcomes included hospitalization, intensive care unit (ICU) admission, mechanical ventilation, and mortality rates. We examined the characteristics of patients who had positive clinical outcomes. We created unadjusted logistic regression models, sequentially adjusting for demographic and comorbidity variables, to assess the independent associations between BMI, patient characteristics, obesity-related comorbidities, and clinical outcomes. RESULTS: From a record of 1.67 million inpatients and outpatients at Froedtert Health Center, 55,299 (BMI: 30.5 ± 7.4 kg/m2, 62.5 % female) tested COVID-19 positive during the study period. 17,580 (31.8 %) patients were admitted to hospitals, and of hospitalized patients required ICU admission. 1038 (36.3 %) required mechanical ventilation, and 462 (44.5 %) died after a positive test for COVID-19. We found female patients show a higher hospitalization rate, while male patients have a higher rate of ICU admission, mechanical ventilation, and mortality. Obesity-related comorbidities are associated with worse outcomes compared to simple obesity without comorbidities. In logistic regression models, we found four similar V-shaped associations between BMI and four clinical outcomes. Patients with a BMI of 25 kg/m2 are at the lowest risk for clinical outcomes. Patients with a BMI lower than 18 kg/m2 or higher than 30 kg/m2 are associated with a higher risk of hospitalization, ICU, mechanical ventilation, and death. After adjusting the model for demographic factors and hypertension and diabetes as two common comorbidities, we found that demographic factors do not significantly increase the risk. Obesity alone does not significantly increase the risk of severe clinical outcomes. Obesity-related comorbidities, on the other hand, resulted in a significantly higher risk of outcomes. CONCLUSION: Obesity alone does not increase the risk of worse clinical outcomes after COVID-19 infection. It may suggest that the worse clinical outcomes of patients with obesity are mediated via hypertension and type 2 diabetes. Patients with obesity and comorbidities have a higher risk of poor outcomes. Obesity-related comorbidities, including hypertension and diabetes, are independently associated with poorer clinical outcomes among COVID-19 patients. At a BMI of more than 30 kg/m2 or less than 18 kg/m2, we found an increase in the risk of severe COVID-19 outcomes leading to hospitalization, ICU, mechanical ventilation, and death. The increased risk of severe outcomes is not attributed to patient characteristics but can be attributed to hypertension and diabetes.

Team principles for successful interdisciplinary research teams.

Interdisciplinary research teams can be extremely beneficial when addressing difficult clinical problems. The incorporation of conceptual and methodological strategies from a variety of research disciplines and health professions yields transformative results. In this setting, the long-term goal of team science is to improve patient care, with emphasis on population health outcomes. However, team principles necessary for effective research teams are rarely taught in health professional schools. To form successful interdisciplinary research teams in cardio-oncology and beyond, guiding principles and organizational recommendations are necessary. Cardiovascular disease results in annual direct costs of $220 billion (about $680 per person in the US) and is the leading cause of death for cancer survivors, including adult survivors of childhood cancers. Optimizing cardio-oncology research in interdisciplinary research teams has the potential to aid in the investigation of strategies for saving hundreds of thousands of lives each year in the United States and mitigating the annual cost of cardiovascular disease. Despite published reports on experiences developing research teams across organizations, specialties and settings, there is no single journal article that compiles principles for cardiology or cardio-oncology research teams. In this review, recurring threads linked to working as a team, as well as optimal methods, advantages, and problems that arise when managing teams are described in the context of career development and research. The worth and hurdles of a team approach, based on practical lessons learned from establishing our multidisciplinary research team and information gleaned from relevant specialties in the development of a successful team are presented.

The correlations among racial/ethnic groups, hypertriglyceridemia, thrombosis, and mortality in hospitalized patients with COVID-19.

Reports of racial and ethnic disparities regarding both rates of infection of the SARS-CoV-2 virus and morbidity of the coronavirus disease-19 (COVID-19) contain profound differences depending on the population. Our previous study has shown that patients with COVID-19 who developed hypertriglyceridemia during hospitalization have a 2.3 times higher mortality rate. However, whether the correlation between hypertriglyceridemia and mortality has disparity among different racial and ethnic groups is unknown. In this study, we investigated the impact of race/ethnicity on the correlation between hypertriglyceridemia and mortality in hospitalized patients with COVID-19. De-identified information from 904 hospitalized patients diagnosed with COVID-19 between March 2020 and June 2021 were extracted from the Medical College of Wisconsin Clinical Data Warehouse. A multivariable regression analysis suggested that the Asians and non-White Hispanics had 4 or 3.9 times higher mortality rate, respectively, after adjusting for age, morbid obesity (BMI ≥40), and gender. The hypertriglyceridemia (≥150 mg/dL) was associated with higher mortality, after adjusting for age, gender, and morbid obesity. The baseline hypertriglyceridemia occurrence had relevantly more consistent percentages among all racial/ethnic groups. However, non-White Hispanic and Asian patients had the highest frequencies of peak hypertriglyceridemia occurrence during hospitalization. The peak hypertriglyceridemia developed during hospitalization correlates with the incidence of thrombosis after adjusting for morbid obesity, age, and sex. In summary, in this retrospective study of 904 hospitalized COVID-19 patients, Asians and non-White Hispanics had a greater likelihood of developing hypertriglyceridemia during hospitalization and mortality than White patients.

Demographic differences in the treatment of unilateral vocal fold paralysis.

Objective: To determine the impact of patient demographics and social determinants of health on treatment pathways for unilateral vocal fold paralysis (UVFP) at a tertiary laryngology clinic. Study design: Retrospective medical record review. Methods: Patient demographics (age, gender, race, ethnicity, and insurance status) were extracted for adults diagnosed with UVFP between 2009 and 2019. Odds ratios for the associations between sociodemographic factors and UVFP treatment pathways were determined by chi-square analyses. Results: A total of 1490 UVFP diagnoses were identified during the study period with the majority being female (58%), White (85%), non-Hispanic (97%), and publicly insured (54%). Five treatment pathways were identified: observation, injection laryngoplasty, voice therapy, laryngeal framework surgery/thyroplasty, and reinnervation surgery. There were 538 patients who underwent observation, 512 injection laryngoplasty, 366 voice therapy, 136 thyroplasty, and 26 laryngeal reinnervation surgery. Males were more likely to undergo injection laryngoplasty than females (OR 1.32; CI 1.08-1.61), whereas females were more likely to undergo voice therapy (OR 1.39; CI 1.09-1.76). Patients with public insurance (OR 1.48; CI 1.03-2.14) and Hispanics (OR 2.60; CI 1.18-5.72) were more likely to undergo thyroplasty. Patients who underwent reinnervation surgery were younger than those in other treatment pathways (median: 39.1 years vs. 50.7-56.1 years). Conclusions: Gender, ethnicity, and insurance status were significantly associated with specific UVFP treatment pathways. Patients with public insurance were more likely to undergo surgical intervention than voice therapy. This data overall supports differences in care pathway utilization for UVFP based on social determinants of health. Level of evidence: Level IV.

Telemedicine and health disparities: Association between patient characteristics and telemedicine, in-person, telephone and message-based care during the COVID-19 pandemic.

Telemedicine has been an essential form of care since the onset of the COVID-19 pandemic. However, telemedicine may exacerbate disparities for populations with limited digital literacy or access, such as older adults, racial minorities, patients of low income, rural residences, or limited English proficiency. From March 2020 to March 2022, this retrospective cohort study analyzed the use of in-person, phone/message, and telemedical care at a single tertiary care center in an oncology department. We investigated the association between economic, racial, ethnic, socioeconomic factors and forms of care, including in-person visits, telemedicine-based visits, and telephone/messages. The study results show that telemedicine utilization is lower among patients 65 and older, female patients, American Indian or Alaska Native patients, uninsured patients, and patients who require interpreters during clinical visits. As a result, it is unlikely that telemedicine will provide equal access to clinical care for all populations. On the other hand, in-person care utilization remains low in low-income and rural-living patients compared to the general population, while telephone and message use remains high in low-income and rural-living patients. We conclude that telemedicine is currently unable to close the utilization gap for populations of low socioeconomic status. Patients with low socioeconomic status use in-person care less frequently. For the disadvantaged, unusually high telephone or message utilization is unlikely to provide the same quality as in-person or telemedical care. Understanding the causes of disparity and promoting a solution to improve equal access to care for all patients is critical.

Standardization of Outcome Measures for Intratympanic Steroid Treatment for Idiopathic Sudden Sensorineural Hearing Loss.

OBJECTIVE: To identify variability in reported hearing outcomes for intratympanic (IT) steroid treatment of idiopathic sudden sensorineural hearing loss (ISSNHL) by comparing outcomes using the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guideline with other published criteria. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary otology practice. PATIENTS: Patients with ISSNHL treated with IT steroid between April 2003 and December 2020. INTERVENTIONS: IT steroid injection and audiometric evaluation. MAIN OUTCOME MEASURES: 1) Rates of full, partial, or no recovery using the AAO-HNS guideline versus other reported criteria, and 2) correlation analyses of demographic and clinical variables with response to IT steroid. RESULTS: Using AAO-HNS reporting criteria, full recovery of the pure-tone average was noted in 25.68% of patients. Applying eight other published outcomes criteria to this patient cohort classified full recovery in 14.87 to 40.54% of patients. Similarly, AAO-HNS criteria classified "no recovery" in 51.35% of our patients, whereas applying the other reported criteria showed an average rate of 62.16% no recovery and as high as 82.43% of patients without recovery. Younger age ( p = 0.003; effect size, 0.924) and IT injection within a week of onset ( p < 0.001; effect size, 1.099) positively correlated with full recovery. There was no impact of prior or concurrent oral steroids, or number of steroid injections on outcome. CONCLUSION: Great variability exists in the literature for assessment of IT steroid outcomes in ISSNHL. Standard reporting of outcomes as per the AAO-HNS SSNHL guideline is recommended to consistently characterize IT steroid efficacy and allow comparison across studies.

Medial orbital wall decompression: Demographics influencing surgical follow-up and complications: Impacts on follow-up and complications.

OBJECTIVE: Identify the impact of demographics and social determinants of health on surgical follow-up and complications after medial orbital wall decompression (MOWD) secondary to thyroid associated orbitopathy (TAO). METHODS: Demographics and social determinants of health (age, sex, race, insurance status) for 46 patients undergoing MOWD secondary to TAO were correlated with post-operative compliance and surgical complications by chi-square analyses. RESULTS: Among 46 patients, 23 were compliant with follow-up. There was no statistically significant difference between compliance and non-compliance based on age (60.25 vs 56.4, p = .41), sex (71.9 % female vs 85.7 % female, p = .31), race (65.6 % white vs 71.4 % white, p = .70) or insurance status (59.4 % private vs 42.9 % private, p = .30). Complications were noted in 50 % of patients of which sinus infection was most common (47.8 % of complications) and epistaxis rare (4.3 % of complications). No correlation was noted between development of complications and compliance (p = .20). Likewise, age, race and insurance status did not correlate with complications. CONCLUSION: For patients undergoing MOWD, no correlations with compliance or complication rate were noted with age, sex, race, or insurance status. A larger cohort may be indicated to identify such patterns. The overall complication rate was 50 % and the increased number of visits may have economic impact. KEY POINTS: This study provides a unique chance to assess demographic correlates of compliance and complication while controlling for surgeon preference. There was no association between sociodemographics and compliance or complications.

Natural Language Processing for Enterprise-scale De-identification of Protected Health Information in Clinical Notes.

Patient privacy is a major concern when allowing data sharing and the flow of health information. Hence, de-identification and anonymization techniques are used to ensure the protection of patient health information while supporting the secondary uses of data to advance the healthcare system and improve patient outcomes. Several de-identification tools have been developed for free-text, however, this research focuses on developing notes de-identification and adjudication framework that has been tested for i2b2 searches. The aim is to facilitate clinical notes research without an additional HIPAA approval process or consent by a clinician or patient especially for narrative free-text notes such as physician and nursing notes. In this paper, we build a scalable, accurate, and maintainable pipeline for notes de-identification utilizing the natural language processing and REDCap database as a method of adjudication verification. The system is deployed at an enterprise-scale where researchers can search and visualize over 45 million de-identified notes hosted in an i2b2 instance.

Establishing an interdisciplinary research team for cardio-oncology artificial intelligence informatics precision and health equity.

Study objective: A multi-institutional interdisciplinary team was created to develop a research group focused on leveraging artificial intelligence and informatics for cardio-oncology patients. Cardio-oncology is an emerging medical field dedicated to prevention, screening, and management of adverse cardiovascular effects of cancer/ cancer therapies. Cardiovascular disease is a leading cause of death in cancer survivors. Cardiovascular risk in these patients is higher than in the general population. However, prediction and prevention of adverse cardiovascular events in individuals with a history of cancer/cancer treatment is challenging. Thus, establishing an interdisciplinary team to create cardiovascular risk stratification clinical decision aids for integration into electronic health records for oncology patients was considered crucial. Design/setting/participants: Core team members from the Medical College of Wisconsin (MCW), University of Wisconsin-Milwaukee (UWM), and Milwaukee School of Engineering (MSOE), and additional members from Cleveland Clinic, Mayo Clinic, and other institutions have joined forces to apply high-performance computing in cardio-oncology. Results: The team is comprised of clinicians and researchers from relevant complementary and synergistic fields relevant to this work. The team has built an epidemiological cohort of ~5000 cancer survivors that will serve as a database for interdisciplinary multi-institutional artificial intelligence projects. Conclusion: Lessons learned from establishing this team, as well as initial findings from the epidemiology cohort, are presented. Barriers have been broken down to form a multi-institutional interdisciplinary team for health informatics research in cardio-oncology. A database of cancer survivors has been created collaboratively by the team and provides initial insight into cardiovascular outcomes and comorbidities in this population.

Analysis of socioeconomic factors in laryngology clinic utilization for treatment of dysphonia.

OBJECTIVE: To evaluate the association between patient socioeconomic and demographic factors and tertiary care utilization for dysphonia in a localized metropolitan area of the American Midwest. METHODS: Multivariate regression analysis was used to correlate patient demographics and population level data (e.g., age, gender, race, insurance, median income, education level) with tertiary laryngology utilization for dysphonia care at our institution between 2000 and 2019. Initial analyses characterized tertiary laryngology utilization rates for all regional ZIP codes and correlated these data with census information for household income and education. Dysphonia patient demographics were compared among populations cared for in our entire academic Otolaryngology department, our health system, and the regional population. RESULTS: Among 1,365,021 patients in our health system, there were 7066 tertiary laryngology visits with a diagnosis of dysphonia. Dysphonia patients as compared to the overall health system were older (62.0 vs. 50.8 years), more likely to be female (63.7 vs. 50.2%) and more likely to have insurance (98.4 vs. 87.5%, all p < .001). Patient and population-level factors including insurance status, education, and black race showed positive correlation with laryngology utilization while median income did not. CONCLUSIONS AND RELEVANCE: Insurance status, education level, and race correlated with utilization of tertiary laryngology services for the evaluation of dysphonia in our community, while median income did not. Black patients utilized tertiary laryngology care at higher rates compared to departmental and regional population utilization data. These results underscore important demographic and disease-specific factors that may affect utilization of subspecialty care in Otolaryngology. LEVEL OF EVIDENCE: IV.

The impact of social determinants of health and clinical comorbidities on post-tympanotomy tube otorrhea.

OBJECTIVES: To measure the impact of social determinants of health and clinical comorbidities on the incidence of post-tympanotomy tube otorrhea (PTTO). METHODS: Retrospective observational cohort study. All children between the ages of 0 and 17 having tympanotomy tube placement between 2009 and 2019. Between group comparisons entailed the calculation of odds ratios (OR) with 95% confidence intervals and associated p-values. RESULTS: Among 12,757 patients who underwent myringotomy and tube placement, 2217 (17.4%) presented with PTTO within 1 year. Race and sex did not correlate with the development of PTTO. Non-Hispanic ethnicity had a negative association with PTTO (OR: 0.80 (0.70-0.91), p < .0001). Insurance status correlated with incidence of PTTO with a higher rate noted among those with public insurance (OR: 1.12 (1.02-1.23), p = .02) and a lower rate among those with private insurance (OR: 0.84 (0.77-0.92), p < .0001). Craniofacial abnormalities had the strongest positive correlation with PTTO, particularly, cleft lip and/or cleft palate (OR>2.24, p < .0001). Immunodeficiency had similar impact on PTTO (OR: 2.38 (1.46-3.91), p < .0001). Asthma and prematurity did not significantly correlate with occurrence of PTTO. CONCLUSION: Higher rates of PTTO correlated strongest with clinical factors; particularly craniofacial abnormalities and immunodeficiency. Social determinants, including private insurance and non-Hispanic ethnicity, were associated with lower rates of PTTO. Race and sex did not show significant correlations.

Telemedicine Adoption during the COVID-19 Pandemic: Gaps and Inequalities.

BACKGROUND: The telemedicine industry has been experiencing fast growth in recent years. The outbreak of coronavirus disease 2019 (COVID-19) further accelerated the deployment and utilization of telemedicine services. An analysis of the socioeconomic characteristics of telemedicine users to understand potential socioeconomic gaps and disparities is critical for improving the adoption of telemedicine services among patients. OBJECTIVES: This study aims to measure the correlation of socioeconomic determinants with the use of telemedicine services in Milwaukee metropolitan area. METHODS: Electronic health record review of patients using telemedicine services compared with those not using telemedicine services within an academic-community health system: patient demographics (e.g., age, gender, race, and ethnicity), insurance status, and socioeconomic determinants obtained through block-level census data in Milwaukee area. The telemedicine users were compared with all other patients using regression analysis. The telemedicine adoption rates were calculated across regional ZIP codes to analyze the geographic patterns of telemedicine adoption. RESULTS: A total of 104,139 patients used telemedicine services during the study period. Patients who used video visits were younger (median age 48.12), more likely to be White (odds ratio [OR] 1.34; 95% confidence interval [CI], 1.31-1.37), and have private insurance (OR 1.43; CI, 1.41-1.46); patients who used telephone visits were older (median age 57.58), more likely to be Black (OR 1.31; CI 1.28-1.35), and have public insurance (OR 1.30; CI 1.27-1.32). In general, Latino and Asian populations were less likely to use telemedicine; women used more telemedicine services in general than men. In the multiple regression analysis of social determinant factors across 126 ZIP codes, college education (coefficient 1.41, p = 0.01) had a strong correlation to video telemedicine adoption rate. CONCLUSION: Adoption of telemedicine services was significantly impacted by the social determinant factors of health, such as income, education level, race, and insurance type. The study reveals the potential inequities and disparities in telemedicine adoption.

Hypertriglyceridemia during hospitalization independently associates with mortality in patients with COVID-19.

BACKGROUND: Alteration in blood triglyceride levels have been found in patients with coronavirus disease 2019 (COVID-19). However, the association between hypertriglyceridemia and mortality in COVID-19 patients is unknown. OBJECTIVE: To investigate the association between alteration in triglyceride level and mortality in hospitalized COVID-19 patients. METHODS: We conducted a retrospective study of 600 hospitalized patients with COVID-19 diagnosis (ICD10CM:U07.1) and/or SARS-CoV-2 positive testing results between March 1, 2020 and December 21, 2020 at a tertiary academic medical center in Milwaukee, Wisconsin. De-identified data, including demographics, medical history, and blood triglyceride levels were collected and analyzed. Of the 600 patients, 109 patients died. The triglyceride value on admission was considered the baseline and the peak was defined as the highest level reported during the entire period of hospitalization. Hypertriglyceridemia was defined as greater than 150 mg/dl. Logistic regression analyses were performed to evaluate the association between hypertriglyceridemia and mortality. RESULTS: There was no significant difference in baseline triglyceride levels between non-survivors (n = 109) and survivors (n = 491) [Median 127 vs. 113 mg/dl, p = 0.213]. However, the non-survivors had significantly higher peak triglyceride levels during hospitalization [Median 179 vs. 134 mg/dl, p < 0.001]. Importantly, hypertriglyceridemia independently associated with mortality [odds ratio=2.3 (95% CI: 1.4-3.7, p = 0.001)], after adjusting for age, gender, obesity, history of hypertension and diabetes, high CRP, high leukocyte count and glucocorticoid treatment in a multivariable logistic regression model. CONCLUSIONS: Hypertriglyceridemia during hospitalization is independently associated with 2.3 times higher mortality in COVID-19 patients. Prospective studies are needed to independently validate this retrospective analysis.

Socioeconomic Determinants of Tertiary Rhinology Care Utilization.

OBJECTIVE: The objective of this study was to determine the impact of patient demographics and socioeconomic factors on the utilization of tertiary rhinology care services in an upper Midwestern academic medical center. STUDY DESIGN: Retrospective review of electronic health records. SETTING: Academic medical center. METHODS: The electronic health record of our academic center was interrogated for the demographics and diagnosis of chronic rhinosinusitis (CRS) among adult patients seen by fellowship-trained rhinologists from 2000 to 2019. Patient characteristics (age, sex, race, insurance status) and population-level data (median income and education level) were compared with utilization of tertiary rhinology services for CRS. Utilization rates were calculated for each regional zip code and correlated with census data for median income and education. The association between determinants of health and tertiary rhinology utilization was assessed by multivariate regression analyses. RESULTS: A total of 8325 patients diagnosed with CRS used tertiary rhinology services. Patients were older (median, 58.9 years) and more likely to be female (57.6%), White (85%), and privately insured (60%) when compared with patients seen across our hospital system (P < .001). Adjusted analyses showed median income, education level, and White race to be independently correlated with tertiary care utilization. Private insurance alone was not an independent contributing factor to access. CONCLUSION: Utilization of tertiary rhinology services correlated with income, race, and education level. Private insurance was not an independent factor. These results highlight social differences in determinants of access to tertiary otolaryngologic care.

The effect of number of healthcare visits on study sample selection in electronic health record data.

INTRODUCTION: Few studies have addressed how to select a study sample when using electronic health record (EHR) data. OBJECTIVE: To examine how changing criterion for number of visits in EHR data required for inclusion in a study sample would impact one basic epidemiologic measure: estimates of disease period prevalence. METHODS: Year 2016 EHR data from three Midwestern health systems (Northwestern Medicine in Illinois, University of Iowa Health Care, and Froedtert & the Medical College of Wisconsin, all regional tertiary health care systems including hospitals and clinics) was used to examine how alternate definitions of the study sample, based on number of healthcare visits in one year, affected measures of disease period prevalence. In 2016, each of these health systems saw between 160,000 and 420,000 unique patients. Curated collections of ICD-9, ICD-10, and SNOMED codes (from CMS-approved electronic clinical quality measures) were used to define three diseases: acute myocardial infarction, asthma, and diabetic nephropathy). RESULTS: Across all health systems, increasing the minimum required number of visits to be included in the study sample monotonically increased crude period prevalence estimates. The rate at which prevalence estimates increased with number of visits varied across sites and across diseases. CONCLUSIONS: In addition to providing thorough descriptions of case definitions, when using EHR data authors must carefully describe how a study sample is identified and report data for a range of sample definitions, including minimum number of visits, so that others can assess the sensitivity of reported results to sample definition in EHR data.