Phage display of environmental protein toxins and virulence factors reveals the prevalence, persistence, and genetics of antibody responses.

Microbial exposures are crucial environmental factors that impact healthspan by sculpting the immune system and microbiota. Antibody profiling via Phage ImmunoPrecipitation Sequencing (PhIP-Seq) provides a high-throughput, cost-effective approach for detecting exposure and response to microbial protein products. We designed and constructed a library of 95,601 56-amino acid peptide tiles spanning 14,430 proteins with "toxin" or "virulence factor" keyword annotations. We used PhIP-Seq to profile the antibodies of ∼1,000 individuals against this "ToxScan" library. In addition to enumerating immunodominant antibody epitopes, we studied the age-dependent stability of the ToxScan profile and used a genome-wide association study to find that the MHC-II locus modulates bacterial epitope selection. We detected previously described anti-flagellin antibody responses in a Crohn's disease cohort and identified an association between anti-flagellin antibodies and juvenile dermatomyositis. PhIP-Seq with the ToxScan library is thus an effective tool for studying the environmental determinants of health and disease at cohort scale.

Baseline factors associated with self-reported disease flares following COVID-19 vaccination among adults with systemic rheumatic disease: results from the COVID-19 global rheumatology alliance vaccine survey.

OBJECTIVE: To examine the frequency of, and risk factors for, disease flare following COVID-19 vaccination in patients with systemic rheumatic disease (SRD). METHODS: An international study was conducted from 2 April to 16 August 2021, using an online survey of 5619 adults with SRD for adverse events following COVID-19 vaccination, including flares of disease requiring a change in treatment. We examined risk factors identified a priori based on published associations with SRD activity and SARS-CoV-2 severity, including demographics, SRD type, comorbidities, vaccine type, cessation of immunosuppressive medications around vaccination and history of reactions to non-COVID-19 vaccines, using multivariable logistic regression. RESULTS: Flares requiring a change in treatment following COVID-19 vaccination were reported by 4.9% of patients. Compared with rheumatoid arthritis, certain SRD, including systemic lupus erythematosus (OR 1.51, 95% CI 1.03, 2.20), psoriatic arthritis (OR 1.95, 95% CI 1.20, 3.18) and polymyalgia rheumatica (OR 1.94, 95% CI 1.08, 2.48) were associated with higher odds of flare, while idiopathic inflammatory myopathies were associated with lower odds for flare (OR 0.54, 95% CI 0.31-0.96). The Oxford-AstraZeneca vaccine was associated with higher odds of flare relative to the Pfizer-BioNTech vaccine (OR 1.44, 95% CI 1.07, 1.95), as were a prior reaction to a non-COVID-19 vaccine (OR 2.50, 95% CI 1.76, 3.54) and female sex (OR 2.71, 95% CI 1.55, 4.72). CONCLUSION: SRD flares requiring changes in treatment following COVID-19 vaccination were uncommon in this large international study. Several potential risk factors, as well as differences by disease type, warrant further examination in prospective cohorts.

Association of anti-HSC70 autoantibodies with cutaneous ulceration and severe disease in juvenile dermatomyositis.

OBJECTIVES: JDM is an inflammatory myopathy characterized by prominent vasculopathy. AECAs are frequently detected in inflammatory and autoimmune diseases. We sought to determine whether AECAs correlate with clinical features of JDM, and thus serve as biomarkers to guide therapy or predict outcome. METHODS: Plasma samples from 63 patients with JDM, 49 patients with polyarticular JIA and 40 juvenile healthy controls were used to detect anti-heat shock cognate 71 kDa protein (HSC70) autoantibodies, a newly identified AECA, in ELISA assays. Clinical features were compared between JDM patients with and without anti-HSC70 autoantibodies. RESULTS: Anti-HSC70 autoantibodies were detected in 35% of patients with JDM, in 0% of patients with JIA (P < 0.0001) and in 0% of healthy donors (P < 0.0001). Both the presence of cutaneous ulcers (59% vs 17%, P < 0.002) and the use of wheelchairs and/or assistive devices (64% vs 27%, P < 0.007) were strongly associated with anti-HSC70 autoantibodies in JDM. High scores on the severity of myositis damage measures at the time of measurement of anti-HSC70 autoantibodies and an increased number of hospitalizations were also associated with anti-HSC70 autoantibodies. Intravenous immunoglobulin therapy was used more often in anti-HSC70 autoantibody-positive patients. CONCLUSION: Anti-HCS70 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies correlating with disease severity.

Development of a model for predicting hospital beds shortage and optimal policies using system dynamics approach.

BACKGROUND: Policymakers use simulation-based models to improve system feedback and model the reality of the problems in the system. This study uses the system dynamics approach to provide a model for predicting hospital bed shortages and determine the optimal policy in Shiraz, Southern Iran. METHODS: This study was designed based on Sterman's system dynamic modeling (SDM) process. Firstly, we determined the main variables affecting bed distribution using a mixed qualitative and quantitative study which includes scoping review, expert panel, Delphi, and DANP. Then, dynamic hypotheses were designed. Subsequently, we held several expert panels for designing the causal and stock-flow models, formulating and testing a simulation model, as well as developing various scenarios and policies. RESULTS: Dynamic modeling process resulted in four scenarios. All of the scenarios predicted a shortage of national hospital beds over a 20-year time horizon. Then, four policies were developed based on the changes in the number of beds and capacity of home care services; finally, the optimal policy was determined. CONCLUSIONS: Due to the high cost of setting up hospital beds, developing and supporting cost-effective home care services, strengthening the insurance coverage of these services, and improving the quantity and quality of community care, considering the real needs of the community could be considered as an optimal option for the future of the city.

Strategies for controlling violence against health care workers: Application of fuzzy analytical hierarchy process and fuzzy additive ratio assessment.

OBJECTIVE: The present study aimed to identify and prioritize control measures of violence against health care workers (HWs) using the fuzzy analytical hierarchy process (FAHP) and fuzzy additive ratio assessment (ARAS-F). BACKGROUND: Occupational violence is a pervasive problem in health care centres. Reducing violence against staff is one of the challenges for health care managers. METHOD: At the first stage, the most common criteria and control options for violence against HWs were identified and extracted using a review of previous studies. At the next stage, criteria for selection of control measures were prioritized using the FAHP. Finally, control measures of workplace violence were prioritized using the ARAS-F method. RESULTS: Results of the FAHP indicated that safety and efficiency were the most important criteria. Results of the ARAS-F also revealed that 'increasing number of security personnel' and 'training staff' were the best recommendations for controlling violence against HWs. CONCLUSION: Based on expert's opinions, administrative measures are the optimal ways to control violence at health centres; therefore, it is suggested that violence control programmes should be more focused on administrative measures. IMPLICATIONS FOR NURSING MANAGEMENT: These results could assist nursing management to take best strategies for controlling occupational violence based on multi-criteria decision-making methods.

Factors Influencing Laboratory Information System Effectiveness Through Strategic Planning in Shiraz Teaching Hospitals.

This study aimed to develop and test a research model that examined 7effective factors on the effectiveness of laboratory information system (LIS) through strategic planning. This research was carried out on total laboratory staff, information technology staff, and laboratory managers in Shiraz (a city in the south of Iran) teaching hospitals by structural equation modeling approach in 2015. The results revealed that there was no significant positive relationship between decisions based on cost-benefit analysis and LIS functionality with LIS effectiveness, but there was a significant positive relationship between other factors and LIS effectiveness. As expected, high levels of strategic information system planning result in increasing LIS effectiveness. The results also showed that the relationship between cost-benefit analysis, LIS functionality, end-user involvement, and information technology-business alignment with strategic information system planning was significant and positive.

Factors influencing decision making for healthcare services outsourcing: A review and Delphi study.

Background: Outsourcing is considered as one of the tools for organizational development and promotion of productivity by managers. In recent years, outsourcing of healthcare services has become significant. The aim of this study was to identify the most important factors influencing the decision making of outsourcing healthcare services. Methods: This study is a combined study. First, the literature was examined to identify the factors influencing decision making for outsourcing. Then, with the aim of consensus on the most important factors affecting the decision making of outsourcing in health services, the panel of experts and Delphi technique were used. Sampling was purposeful. Results: In the selected articles, a total of 180 factors were extracted. The members of the panel of experts from these 180 factors selected 29 sub-factors in the form of six main factors: strategy, quality, management, technology, performance feature, and economy, as the most important factors affecting the outsourcing of services. Finally, the results of Delphi showed that 22 sub-factors were more important in outsourcing decision making at healthcare services. Conclusion: The study showed that the decision making to outsource health services is a complex and multi-criteria decision. Therefore, when deciding to outsource healthcare services, attention should be paid to various factors, such as strategy, quality, management, technology, and economics.

Assessing the Quality of Services Provided in the Teaching Hospitals: A Case Study of Iran.

Service quality is the most important factor in the success of health care organizations; because of their vital and important services, even very small errors can be followed by great and irreparable harm and damage. This study aimed to assess the quality of services provided in the teaching hospitals affiliated to Shiraz University of Medical Sciences in 2015. This is an applied, cross-sectional, and descriptive-analytical study conducted in 2015 in the teaching hospitals affiliated to Shiraz University of Medical Sciences. A sample of 290 inpatients with at least 2 days of admission to hospital was selected using stratified sampling proportional to size and simple random sampling methods. The results showed that there were significant negative gaps in all dimensions (P > .001), and the highest and lowest means and SD of negative gaps were related to empathy (-1.35 ± 1.4) and assurance (-0.52 ± 0.95). Moreover, the results showed that there was a significant negative correlation between the patients' age and the total mean of the patients' expectations. According to the results, the studied hospitals had not been able to meet the expectations of their patients in any of the service quality dimensions. Therefore, to improve the service quality dimensions, the authors recommend holding training courses on how to interact with patients and meet their needs, providing adequate and proper information about the diseases and their treatment for the patients, having adequate medical staff, and so on.

The Effects of Transformational Leadership and Mediating Factors on the Organizational Success Using Structural Equation Modeling: A Case Study.

This study was undertaken to determine the effects of transformational leadership (TL) and mediating factors on organizational success (OS) from the administrative, financial, and support employees' perspective in teaching hospitals affiliated with Shiraz University of Medical Sciences using structural equation modeling. Three hundred administrative and financial employees were selected, using stratified sampling proportional to size and simple random sampling. Data were collected using 5 questionnaires and analyzed using SPSS 21.0 and Lisrel 8.5 through Pearson correlation coefficient and path analysis and confirmatory factor analysis methods. Results showed that TL had significant positive effects on the 3 mediating factors, including organizational culture (t = 15.31), organizational citizenship behavior (OCB) (t = 10.06), and social capital (t = 10.25). Also, the organizational culture (t = 2.26), OCB (t = 3.48), and social capital (t = 7.41) had significant positive effects on OS. According to the results, TL had an indirect effect on OS. Therefore, organizations can achieve more success by strengthening organizational culture, OCB, and social capital through using transformational leadership style. Therefore, in order to increase OS, the following recommendations are made: supporting and encouraging new ideas in the organization, promoting teamwork, strengthening intergroup and intragroup relationships, planning to strengthen and enrich the social and organizational culture, considering the promotion of social capital in the employee training, establishing a system to give rewards to the employees performing extra-role activities, providing a suitable environment for creative employees, and so on.

The Effects of Supervisors' Support and Mediating Factors on the Nurses' Job Performance Using Structural Equation Modeling: A Case Study.

Nurses are the largest group and an important part of the providers in the health care systems that who a key role in hospitals. Any defect and deficiency in their work can result in irreversible outcomes. This study aimed to determine the effect of supervisors' support and mediating factors on the job performance (JOBPER) of 400 nurses working in the teaching hospitals affiliated to Shiraz University of Medical Sciences, using structural equation modeling. The results showed that the supervisor's support had a significant negative effect on work-family conflict (t = -2.57) and a positive effect on organizational commitment (t = 4.03); Work-family conflict had a significant positive effect on job stress (t = 11.24) and a negative effect on organizational commitment (t = -3.35) and JOBPER (t = -2.29). Family-work conflict had a positive effect on job stress (t = 4.48) and a negative effect on organizational commitment (t = -2.54). Finally, job stress had a negative effect (t = -3.30), and organizational commitment showed a positive effect (t = 5.96) on the studied nurses' JOBPER. According to the results, supervisor's support could influence JOBPER through reducing work-family conflict and increasing organizational commitment. Therefore, to improve the nurses' JOBPER in the hospitals, some strategies are recommended.

A causal model of antecedents with burnout focusing on the intermediate role of hardy personality in Iranian nurses.

Nowadays burnout is a common issue in all health systems and therapeutic professions. Burnout is caused by job stressors and results in reduction in output, increase in absenteeism and health expenses, behavioral changes, and sometimes drugs abuse. Nonetheless, people who have hardy personalities experience less exhaustion. The present research aimed to present a causal model of antecedents with burnout to emphasize the intermediate role of hardy personality in the nurses working in the public hospitals of Shiraz, Iran. The study data were collected using the Nursing Burnout Scale questionnaire (Int J Nurs Stud. 2008;45(3):418-427). In addition, the structural equation method was used as a model in order to determine the relationship between the variables. The suggested pattern in this research was checked by Leasrel software, version 8.5. The study results showed that antecedents, such as incorrect supervision, responsibility, and workload, have a significant effect on burnout. However, mediated hardy personality had no effect on burnout. The results also showed that the people who had hardy personality could manage the stressful situations well and, consequently, rarely experience burnout. Overall, if the job stressors are existent in the job environment and the individuals cannot eradicate them, they will cause burnout outbreak.

Myositis-Associated Autoantibodies in Patients With Juvenile Myositis Are Associated With Refractory Disease and Mortality.

OBJECTIVE: Myositis-associated autoantibodies (MAAs) have been associated with overlap myositis, certain disease manifestations such as interstitial lung disease (ILD), and worse prognosis in the idiopathic inflammatory myopathies. MAAs overall remain largely uncharacterized in patients with juvenile-onset myositis. Moreover, it is unknown whether the number of MAAs is associated with disease severity. METHODS: Patients with juvenile myositis in cross-sectional natural history studies who underwent testing for myositis autoantibodies were included. Demographics, myositis autoantibodies, clinical characteristics, medications received, and outcomes of those with and without MAAs were compared. Multivariable logistic regression was performed to determine whether the number of MAAs detected was associated with severe disease features. RESULTS: Among 551 patients, 36% had an MAA and 13% had more than one MAA. Among those who were MAA positive, there was a higher frequency of overlap myositis (18% vs 5.9%, P < 0.001). MAA positivity was associated with certain clinical features, including Raynaud phenomenon (odds ratio [OR] 2.44, 95% confidence interval [CI] 1.41-4.28) and ILD (OR 3.43, 95% CI 1.75-6.96), as well as a chronic disease course (OR 1.72, 95% CI 1.10-2.72) and mortality (OR 3.76, 95% CI 1.72-8.43). The number of MAAs was also associated with mortality (OR 1.83, 95% CI 1.16-2.86). CONCLUSION: MAAs were prevalent in a large cohort of patients with juvenile myositis. ILD, refractory disease, and mortality were associated with MAA positivity. Prospective studies are needed to determine whether early detection of MAAs may lead to improved outcomes for patients with juvenile myositis.

The effects of supervisors' supportive role, job stress, and work-family conflicts on the nurses' attitudes.

This study developed and tested a research model that examined the effects of supervisor support (SUPPORT), work-family conflict (W-FCON), family-work conflict (F-WCON), and job stress (JSTRESS) on a number of selected consequences using data collected from nurses and nurse axillaries in Shiraz University of Medical Sciences hospitals in Fars province (south of Iran). The results demonstrated that W-FCON and F-WCON exerted a significant positive influence on JSTRESS. Contrary to the study hypothesis, the results did not provide any empirical support for the significant negative relationship between W-FCON, F-WCON, and JSTRESS with family satisfaction (FSAT). The findings further revealed that higher JSTRESS led to lower life satisfaction (LSAT). As expected, high levels of FSAT resulted in increased LSAT. However, this study failed to find significant negative relationships between conflicts in the work-family interface and LSAT. The results also revealed that JSTRESS was not significantly associated with LSAT. Consonant with the study hypotheses, W-FCON, F-WCON, and JSTRESS were found to be significant for turnover intentions, whereas LSAT did not. Implications for managers and future research directions are presented.

An evaluation of the risk factors associated with implementing projects of health information technology by fuzzy combined ANP-DEMATEL.

BACKGROUND: Application of a Clinical Information System (CIS) like Electronic Patient Record (EPR), PACS system and CPOE has turned into one of the most important criteria of priorities of health care systems. The aims of the clinical information system include improving the physicians' efficiency level, integrating the caring process, and expanding the fuzzy quality of the services offered to patients. Achievement of these benefits in reality is not an easy task, and there are lots of plans in this field which are doomed to failure. About 50% of the implementation plans of clinical information systems in health care organizations have failed, and this trend is significantly affecting industrial countries. Proper implementation of hospital information systems lies in identifying and assessing the relationships among the most important risk factors of fuzzy. The present study aimed to provide an applicable model for identifying, ranking and evaluating the risk factors associated with projects of clinical information technology in hospitals of Shiraz University of Medical Sciences. METHOD: This is an applied study which evaluates the risk factors associated with implementation of clinical information technology projects in hospitals of Shiraz Medical Sciences University. The participants consisted of professionals and senior experts of clinical information technology. Fuzzy logic was used in this study. We also applied ANP-DEMATEL combined model with fuzzy procedure to provide the analytic model of the study. RESULTS: According to the study findings, lack of top-executive supports, and unstable organizational environment were the two most important risk factors, while the main organizational factors and technology were also highly important. In addition, the factors associated with technology had the highest influence on the other studied risk factors. CONCLUSION: Hospital authorities can benefit from this proposed model to reduce the risk of implementing the projects of clinical information technology and improve the success coefficient of the risk of such projects.

Risk assessment of probable human errors in the scaffold erection and dismantling procedure: a fuzzy approach.

Objectives. Despite widespread use of scaffolds on construction sites, they are the most common causes of accidents, injuries and fatalities in this sector. About 80-90% of all occupational accidents occur as a result of human factors. On construction sites, proper erection/dismantling of scaffold is possibly the most essential factor in preventing accidents as it is one of the factors reported to be highly statistically significant in correlation to a high overall scaffold safety rating. Therefore, analysis of human errors (HEs) caused by scaffolders is important to be implemented. The main objective of this study was to evaluate possible HEs during scaffold erection and dismantling (SE&D). Methods. Stages involved were identified using hierarchical task analysis (HTA). Risk values of HEs were then evaluated using the fuzzy analytical hierarchy process (FAHP). Results. Our findings indicate that the highest and lowest risk values were related to the errors of 'failure to reattach braces and connections prior to dismantling scaffolds' and 'insufficient preparation of the firm foundation', respectively. Conclusion. This study formulates a method to estimate the risk of potential HEs in SE&D.

Development of a scenario-based blood bank model to maximize reducing the blood wastage.

INTRODUCTION: Blood is a valuable as well as a perishable commodity that has a limited lifespan. So, keeping it in a blood bank requires careful attention and management. In this study, a management model has been designed for the blood bank that can cover all the requests sent through the hospital subunits in such a way that it has the least waste. MATERIALS AND METHODS: First, by examining the blood inventory system of a hospital, the number of inventories per month and the distribution of blood products in subunits of the hospital, and the amount of blood wastage every six months were estimated. Then, using ARENA simulation, all parts of the blood bank, including the request section, emergency blood section, donated blood section, and other sections were simulated. Finally, 10 scenarios were extracted by placing various parameters and the best scenarios were discussed and concluded. RESULTS AND DISCUSSION: The scenarios for the four blood groups included A, B, AB, and O were applied for six months in one year. The results showed that if the amount of blood injected into the blood bank is appropriate and at the right time, the amount of wastage can be reduced by up to 80% for most of the blood groups. CONCLUSION: The results of this study showed that if the system of receiving blood products built upon a precise management model is predetermined and placed with appropriate parameters, the amount of wastage will be reduced to the minimum possible number.

The Geospatial Distribution of Myositis and Its Phenotypes in the United States and Associations With Roadways: Findings From a National Myositis Patient Registry.

Background: Little is known about the spatial distribution of idiopathic inflammatory myopathies (IIM) in the United States (U.S.), or their geospatial associations. Methods: We studied a national myositis patient registry, with cases diagnosed in the contiguous U.S. from 1985-2011 and comprised of dermatomyositis (DM, n = 484), polymyositis (PM, n = 358), and inclusion body myositis (IBM, n = 318) patients. To assess the association of myositis prevalence with distance from roads, we employed log-Gaussian Cox process models, offset with population density. Results: The U.S. IIM case distribution demonstrated a higher concentration in the Northest. DM, IBM, and cases with lung disease were more common in the East, whereas PM cases were more common in the Southeast. One area in the West and one area in the South had a significant excess in cases of DM relative to PM and of cases with lung disease relative to those without lung disease, respectively. IIM cases tended to cluster, with between-points interactions more intense in the Northeast and less in the South. There was a trend of a higher prevalence of IIM and its major phenotypes among people living within 50 m of a roadway relative to living beyond 200 m. Demographic characteristics, rural-urban commuting area, and female percentage were significantly associated with the prevalence of IIM and with major phenotypes. Conclusions: Using a large U.S. database to evaluate the spatial distribution of IIM and its phenotypes, this study suggests clustering in some regions of the U.S. and a possible association of proximity to roadways.

Environmental factors associated with juvenile idiopathic inflammatory myopathy clinical and serologic phenotypes.

BACKGROUND: Environmental exposures have been associated with the juvenile idiopathic inflammatory myopathies (JIIM). We undertook a questionnaire-based study to evaluate patient-reported exposures as possible risk factors for JIIM. FINDINGS: One-hundred-seven patients with JIIM were enrolled in a myositis natural history protocol and completed environmental questionnaires. Frequencies of exposures in clinical and myositis-specific autoantibody (MSA) groups were examined. Patients with juvenile dermatomyositis (JDM) and juvenile connective tissue myositis (JCTM) more frequently received an immunization within 1 year of diagnosis compared to juvenile polymyositis (57.5 and 71.4% vs 0.0%, p ≤ 0.017). JCTM patients were more often underweight at diagnosis relative to JDM patients (42.9% vs 7.0%, p = 0.002). MSA-negative patients more frequently had gastroenteritis within a year of diagnosis compared to patients with anti-MDA5 autoantibodies (28.6% vs 0.0%, p = 0.032). Heavy exercise was more frequent in MSA-negative and anti-MDA5 groups compared to the anti-TIF-1 autoantibody group (42.9 and 35.3% vs. 9.0%, p ≤ 0.047). Medications received within 1 year of diagnosis were more frequent in MSA-negative patients relative to those with anti-MDA5 autoantibodies (92.9% vs. 52.8% p = 0.045). Being breastfed > 6 months was more frequent in MSA-negative patients (88.9%) compared to anti-TIF-1 and anti-MDA5 autoantibody groups (41.2 and 28.6%, p ≤ 0.036). CONCLUSIONS: Certain environmental exposures prior to diagnosis differed among clinical and serologic subgroups of JIIM, suggesting additional exposures to be explored as possible risk factors for JIIM phenotypes.

Occupational stressors among firefighters: application of multi-criteria decision making (MCDM)Techniques.

BACKGROUND: Firefighters are exposed to a wide range of occupational stressors due to the nature of their job. Multi-criteria decision-making technique (MCDM) is a method for identifying, evaluating, and preventing occupational stressors among firefighters. The purpose of this study was to identify and prioritize the occupational stressors among firefighters using the fuzzy delphi method (FDM) and fuzzy analytical hierarchy process (FAHP). METHODS: This qualitative-descriptive study was carried out in two stages. First, the most important occupational stressors of firefighters were identified and screened using a systematic review of scientific references and expert opinions based on the FDM. Then, all of the screened stressors were weighted and prioritized by the FAHP using the opinions of experts. All results were analyzed using Excel software. RESULTS: Among, the 52 occupational stressors of firefighters identified in the first stage, 27 stressors were selected to enter into the FAHP. The FAHP results showed that among the four main dimensions, the weight of managerial factors (0.358) was more than other dimensions. The overall result of the study, regardless of the stressors' main dimensions showed that the most important stressors among firefighters were financial strain due to inadequate pay, fear of explosion at incident scenes, toxic smoke, and gases produced at fires and lack of attention given to job safety by management, respectively. CONCLUSION: According to the results of the study, most occupational stressors of the firefighters are caused by organizational factors. Therefore, the implementation of management strategies to reduce the occupational stress of firefighters is recommended.

Association of Ultraviolet Radiation Exposure With Dermatomyositis in a National Myositis Patient Registry.

OBJECTIVE: Dermatomyositis (DM) has been associated with geospatial differences in ultraviolet (UV) radiation, but the role of individual determinants of UV exposure prior to diagnosis is unknown. The objective was to examine the role of those individual determinants. METHODS: We analyzed questionnaire data from 1,350 adults in a US national myositis registry (638 with DM, 422 with polymyositis [PM], and 290 with inclusion body myositis [IBM] diagnosed at ages 18-65 years), examining the likelihood of DM compared with PM and IBM diagnosis, in relation to self-reported sunburn history and job- and hobby-related sun exposures in the year prior to diagnosis. We estimated odds ratios (ORs) and 95% confidence intervals (95% CIs) using logistic regression adjusted for age, skin tone, and sex, to determine the association of individual UV exposures with DM diagnosis. We also evaluated the proportion of DM by maximum daily ambient UV exposure, based on UVB erythemal irradiances for participant residence in the year prior to diagnosis. RESULTS: DM was associated with sunburn in the year before diagnosis (2 or more sunburns OR 1.77 [95% CI 1.28-2.43] versus PM/IBM; 1 sunburn OR 1.44 [95% CI 1.06-1.95]) and with having elevated job- or hobby-related sun exposure (high exposure OR 1.64 [95% CI 1.08-2.49] or moderate exposure OR 1.35 [95% CI 1.02-1.78] versus low or no exposure). Ambient UV intensity was associated with DM in females (ß = 3.97, P = 0.046), but not overall. CONCLUSION: Our findings suggest that high or moderate personal exposure to intense sunlight is associated with developing DM compared with other types of myositis. Prospective research on UV exposure as a modifiable risk factor for DM is warranted.