Pediatric Orthopaedic Surgeon Time Utilization in Clinic: A Pilot Study.

BACKGROUND: The purpose of this study is to quantify how pediatric orthopaedic surgeons spend time in clinic. METHODS: Two pediatric orthopaedic surgeons were individually observed and activities were timed during 3 clinic sessions. One medical student observed and recorded the time using a data collection sheet and a watch. The duration of each clinic session was 4 hours and a new patient was seen every 20 minutes. Data was collected in 7 categories including: time with the patient; time with staff; time listening to the resident presentations, time teaching, time multitasking, time dictating, and time on the electronic medical record (EMR). The number of computer mouse clicks needed to complete each patient encounter was also recorded. The Cerner EMR system was used (Cerner Inc. North Kansas City, MO). RESULTS: Thirty-six percent of the physician's time was spent on the EMR. Thirty-five percent of time was spent with the patient, 7% was spent dictating, 7% teaching, 5% multitasking, 6% with staff, and 4% listening to resident presentations. Overall, during a 20-minute patient visit, 7.2 minutes was spent on the EMR. During a 4-hour clinic, 87 minutes was spent on the EMR. During a full day of clinic-two 4-hour sessions-173 minutes were spent on the EMR. The average number of computer mouse clicks to complete a patient encounter was 70 (range: 42 to 110). A total of 1680 clicks were needed to see 24 patients in a typical 2 session clinic. CONCLUSION: Pediatric orthopaedic surgeons spend more time on the EMR than with patients. About 70 computer mouse clicks are needed per patient encounter. The excessive computer time can diminish the patient-physician relationship. Click fatigue in physicians is real and needs to be resolved by improved EMR technology, utilization of medical scribes, or a return to partial use of paper. LEVEL OF EVIDENCE: Level IV-an observational study.

A Prospective, Randomized, Double-Blinded Controlled Trial Comparing Ibuprofen and Acetaminophen Versus Hydrocodone and Acetaminophen for Soft Tissue Hand Procedures.

PURPOSE: To compare the efficacy of opioid versus nonopioid analgesic regimens after elective, soft tissue hand surgery. We hypothesized that there would be no difference in patient-perceived pain relief between these 2 groups. METHODS: This prospective, randomized, double-blinded controlled trial included patients undergoing elective soft tissue hand procedures (carpal tunnel release, trigger finger release, first dorsal compartment release, or ganglion cyst excision). Patients were randomized before surgery into 2 treatment groups: acetaminophen/hydrocodone 325/5 mg (AH, opioid group) or acetaminophen/ibuprofen 500/400 mg (AIBU, nonopioid group) and followed for 2 weeks after surgery evaluating daily pain intensity scores-visual analog scale (VAS), medication pain relief (Likert pain relief score), need for rescue opioid prescription at 1 week, and days until pain-free. RESULTS: Sixty patients were randomized, 30 in the AH group and 30 in the AIBU group. There was no difference in the average VAS score. There was improved pain relief in the AIBU group, but the difference did not reach significance. There was no difference in time until pain-free, with a median of 5 days in the AH group and 3 days in the AIBU group. Two patients in each group required rescue opioid medication. Side effects were significantly more common in the AH group (n = 7; 23%) than the AIBU group (n = 1; 3%), but none were severe. CONCLUSIONS: We recommend surgeons consider a combination of acetaminophen and ibuprofen as a safe and effective postoperative pain regimen for soft tissue hand surgery procedures. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic I.

Dominant regions and drivers of the variability of the global land carbon sink across timescales.

Net biome productivity (NBP) dominates the observed large variation of atmospheric CO2 annual increase over the last five decades. However, the dominant regions controlling inter-annual to multi-decadal variability of global NBP are still controversial (semi-arid regions vs. temperate or tropical forests). By developing a theory for partitioning the variance of NBP into the contributions of net primary production (NPP) and heterotrophic respiration (Rh ) at different timescales, and using both observation-based atmospheric CO2 inversion product and the outputs of 10 process-based terrestrial ecosystem models forced by 110-year observational climate, we tried to reconcile the controversy by showing that semi-arid lands dominate the variability of global NBP at inter-annual (<10 years) and tropical forests dominate at multi-decadal scales (>30 years). Results further indicate that global NBP variability is dominated by the NPP component at inter-annual timescales, and is progressively controlled by Rh with increasing timescale. Multi-decadal NBP variations of tropical rainforests are modulated by the Pacific Decadal Oscillation (PDO) through its significant influences on both temperature and precipitation. This study calls for long-term observations for the decadal or longer fluctuations in carbon fluxes to gain insights on the future evolution of global NBP, particularly in the tropical forests that dominate the decadal variability of land carbon uptake and are more effective for climate mitigation.

A genome-wide association study of men with symptoms of testicular dysgenesis syndrome and its network biology interpretation.

BACKGROUND: Testicular dysgenesis syndrome (TDS) is a common disease that links testicular germ cell cancer, cryptorchidism and some cases of hypospadias and male infertility with impaired development of the testis. The incidence of these disorders has increased over the last few decades, and testicular cancer now affects 1% of the Danish and Norwegian male population. METHODS: To identify genetic variants that span the four TDS phenotypes, the authors performed a genome-wide association study (GWAS) using Affymetrix Human SNP Array 6.0 to screen 488 patients with symptoms of TDS and 439 selected controls with excellent reproductive health. Furthermore, they developed a novel integrative method that combines GWAS data with other TDS-relevant data types and identified additional TDS markers. The most significant findings were replicated in an independent cohort of 671 Nordic men. RESULTS: Markers located in the region of TGFBR3 and BMP7 showed association with all TDS phenotypes in both the discovery and replication cohorts. An immunohistochemistry investigation confirmed the presence of transforming growth factor ß receptor type III (TGFBR3) in peritubular and Leydig cells, in both fetal and adult testis. Single-nucleotide polymorphisms in the KITLG gene showed significant associations, but only with testicular cancer. CONCLUSIONS: The association of single-nucleotide polymorphisms in the TGFBR3 and BMP7 genes, which belong to the transforming growth factor ß signalling pathway, suggests a role for this pathway in the pathogenesis of TDS. Integrating data from multiple layers can highlight findings in GWAS that are biologically relevant despite having border significance at currently accepted statistical levels.

Acute Exertional Bilateral Thigh Compartment Syndrome in a Patient with Rhabdomyolysis After Spin Class: A Case Report.

CASE: A healthy 24-year-old woman developed rhabdomyolysis and acute bilateral thigh compartment syndrome after 10 minutes of spin class. She was successfully managed with early recognition, aggressive fluid resuscitation, and prompt bilateral surgical decompressive fasciotomy. CONCLUSION: Rhabdomyolysis with acute compartment syndrome is a rare but devastating combination of conditions. A high suspicion for rhabdomyolysis and progression to acute compartment syndrome is warranted for any patient presenting with increasing pain even with a limited history of trauma or exertion. Early recognition and medical and surgical treatment are paramount to preventing permanent damage.

How Are Radial Height and Radial Shortening Defined in the Treatment of Distal Radius Fractures? A Critical Review.

BACKGROUND: Radial height is a radiographic parameter used to guide the treatment of distal radius fractures. However, it is often used synonymously with other terms, and there are substantial discrepancies in its measurement/definition. These discrepancies can alter the measurement of radial height and affect treatment decisions. The purpose of this review is to identify the different definitions of radial height in the literature relevant to distal radius fractures. METHODS: A literature review was conducted in the PubMed/MEDLINE database from inception to 2022. Full-length, English-language studies that pertained to distal radius fractures and reported radial height as a recorded measurement were included. The method of radial height measurement (definition) was extracted from included studies. Level of evidence was determined by the Oxford Centre for Evidence-based Medicine Levels of Evidence tool. RESULTS: A total of 385 studies were identified. Of these, 183 (47.5%) did not provide a definition for radial height. Of the studies that defined radial height, 50.9% (103/202) measured radial height from the radial styloid to the distal ulna, 10.9% (22/202) measured from the radial styloid to the distal radius, and 29.2% (59/202) were "other" definitions. CONCLUSIONS: There is substantial discrepancy in the way that radial height is measured and reported. We advocate for a standardized measurement of radial height (synonymous with radial length) from the radial styloid to the distal ulnar articular surface. Radial shortening is a different measurement and requires comparison with a reference value.

Science advocacy in political rhetoric and actions.

'Science' is a proportionately small but recurring constituent in the rhetorical lexicon of political leaders. To evaluate the use of science-related content relative to other themes in political communications, we undertake a statistical analysis of keywords in U.S. Presidential State of the Union (SOTU) addresses and Presidential Budget Messages (PBM) from Truman (1947) to Trump (2020). Hierarchical clustering and correlation analyses reveal proximate affinities between 'science' and 'research', 'space', 'technology', 'education', and 'climate'. The keywords that are least correlated with 'science' relate to fiscal ('inflation', 'tax') and conflict-related themes ('security', 'war', 'terror'). The most ubiquitous and frequently used keywords are 'economy' and 'tax'. Science-related keywords are used in a positive (promotional) rhetorical context and thus their proportionality in SOTU and PBM corpora is used to define fields of science advocacy (public perception advocacy, funding advocacy, advocacy) for each president. Monte Carlo simulations and randomized sampling of three elements: language (relative frequency of usage of science-related keywords), funding (proposed funding and allocated discretionary funding of science agencies), and actions (e.g. expediency of science advisor appointments, (dis-) establishment of science agencies) are used to generate a science advocacy score (SAS) for each president. The SAS is compared with independent survey-based measures of political popularity. A myriad of political, contextual, and other factors may contribute to lexical choices, policy, and funding actions. Within this complex environment 'science' may have political currency under certain circumstances, particularly where public and political perceptions of the value of science to contribute to matters of priority align. Supplementary Information: The online version contains supplementary material available at 10.1007/s10669-022-09875-x.

Golf cart injuries in children: the experience of trauma centers in a single state in the USA.

Golf carts remain a source of morbidity in children. We aimed to establish the incidence and injury characteristics of pediatric patients injured due to golf cart usage over an 11-year period. This is a retrospective study using a single state trauma database of patients ages 0-17 years admitted to a trauma center and who sustained injures while a golf cart was in use. Thirteen Pediatric and Adult Trauma Centers within the state of Pennsylvania were evaluated from 1 January 2004 to 31 December 2014. The inclusion criteria were met by 108 patients. The mean annual incidence of injuries was 0.35/100 000. The median age of patients was 11 years. The median hospital length of stay and injury severity score were 2 days and 9.5, respectively. The majority of the patients (75.9%) sustained at least one bone fracture. Skull fractures were more prevalent (43.5%), whereas extremity fractures were sustained by 26.9% of patients. Intracranial hemorrhages were sustained by 29.6% of patients. Ejections and rollovers accounted for 58.3% and 31.4% of patient injuries, respectively. The concussion rate was 26.9%. Neither age group nor sex was associated with a difference in fractures, intracranial hemorrhage or concussions. Golf cart injuries in pediatric patients commonly stem from ejections and rollover mechanisms resulting in skull fractures, extremity fractures, intracranial hemorrhages and concussions. The overall incidence of injury was 0.35 cases per 100 000. Further efforts are needed to increase awareness of these injuries and modify regulations regarding the use of golf carts in the pediatric population.

Array-based gene discovery with three unrelated subjects shows SCARB2/LIMP-2 deficiency causes myoclonus epilepsy and glomerulosclerosis.

Action myoclonus-renal failure syndrome (AMRF) is an autosomal-recessive disorder with the remarkable combination of focal glomerulosclerosis, frequently with glomerular collapse, and progressive myoclonus epilepsy associated with storage material in the brain. Here, we employed a novel combination of molecular strategies to find the responsible gene and show its effects in an animal model. Utilizing only three unrelated affected individuals and their relatives, we used homozygosity mapping with single-nucleotide polymorphism chips to localize AMRF. We then used microarray-expression analysis to prioritize candidates prior to sequencing. The disorder was mapped to 4q13-21, and microarray-expression analysis identified SCARB2/Limp2, which encodes a lysosomal-membrane protein, as the likely candidate. Mutations in SCARB2/Limp2 were found in all three families used for mapping and subsequently confirmed in two other unrelated AMRF families. The mutations were associated with lack of SCARB2 protein. Reanalysis of an existing Limp2 knockout mouse showed intracellular inclusions in cerebral and cerebellar cortex, and the kidneys showed subtle glomerular changes. This study highlights that recessive genes can be identified with a very small number of subjects. The ancestral lysosomal-membrane protein SCARB2/LIMP-2 is responsible for AMRF. The heterogeneous pathology in the kidney and brain suggests that SCARB2/Limp2 has pleiotropic effects that may be relevant to understanding the pathogenesis of other forms of glomerulosclerosis or collapse and myoclonic epilepsies.

Air quality and health impact of 2019-20 Black Summer megafires and COVID-19 lockdown in Melbourne and Sydney, Australia.

Poor air quality is an emerging problem in Australia primarily due to ozone pollution events and lengthening and more severe wildfire seasons. A significant deterioration in air quality was experienced in Australia's most populous cities, Melbourne and Sydney, as a result of fires during the so-called Black Summer which ran from November 2019 through to February 2020. Following this period, social, mobility and economic restrictions to curb the spread of the COVID-19 pandemic were implemented in Australia. We quantify the air quality impact of these contrasting periods in the south-eastern states of Victoria and New South Wales (NSW) using a meteorological normalisation approach. A Random Forest (RF) machine learning algorithm was used to compute baseline time series' of nitrogen dioxide (NO2), ozone (O3), carbon monoxide CO and particulate matter with diameter < 2.5 µm (PM2.5), based on a 19 year, detrended training dataset. Across Victorian sites, large increases in CO (188%), PM2.5 (322%) and ozone (22%) were observed over the RF prediction in January 2020. In NSW, smaller pollutant increases above the RF prediction were seen (CO 58%, PM2.5 80%, ozone 19%). This can be partly explained by the RF predictions being high compared to the mean of previous months, due to high temperatures and strong wind speeds, highlighting the importance of meteorological normalisation in attributing pollution changes to specific events. From the daily observation-RF prediction differences we estimated 249.8 (95% CI: 156.6-343.) excess deaths and 3490.0 (95% CI 1325.9-5653.5) additional hospitalisations were likely as a result of PM2.5 and O3 exposure in Victoria and NSW. During April 2019, when COVID-19 restrictions were in place, on average NO2 decreased by 21.5 and 8% in Victoria and NSW respectively. O3 and PM2.5 remained effectively unchanged in Victoria on average but increased by 20 and 24% in NSW respectively, supporting the suggestion that community mobility reduced more in Victoria than NSW. Overall the air quality change during the COVID-19 lockdown had a negligible impact on the calculated health outcomes.

Patient Perceptions of COVID-19 Precautions and Their Effects on Experiences With Hand Surgery.

PURPOSE: The purpose of this study is to evaluate patient perceptions of COVID-19 precautions and how these precautions have affected their hand and upper extremity surgery experience. METHODS: We sent an 18-item survey to 1,213 patients who underwent elective hand and upper extremity surgery at 1 academic institution from October 2020 to January 2021. The survey consisted of questions related to patient demographics, treatment delays due to COVID-19, and patient perceptions of COVID-19 precautions. Descriptive statistics were performed to analyze the survey responses. Responses for patients aged 18-50 and 51+ were compared using a chi-square analysis for categorical variables and a Student t-test for continuous variables. RESULTS: Out of 1,213 invitations, 384 survey respondents completed the survey (31.6%). Of the respondents, 16.8% reported delaying medical treatment for an average of 123.2 days because of COVID-19. The preventative measures were found to be adequate by 95% of patients. Only 2.6% of patients reported experiencing surgical delays due to preoperative COVID-19 testing or other COVID-19-related precautions. COVID-19 testing was seen as necessary by 88% of patients, and 74% did not find COVID-19 testing to be a barrier to their surgery. Patients aged 51+ were more likely to delay seeking medical treatment than younger patients (19.3% vs 9.1%, respectively). Furthermore, those that did delay seeking treatment waited longer on average than their younger counterparts (136.1 vs 72.9 days, respectively). CONCLUSIONS: In conclusion, patients undergoing hand and upper extremity surgery typically do not find COVID-19 precautions to be a significant barrier to care and understand their importance. Despite this, many patients, particularly older ones, are delaying medical care for extended periods of time. It is important for hand surgeons to acknowledge their patients' perspectives and work to educate patients on evolving surgical safety guidelines. CLINICAL RELEVANCE: Patient perspectives of current COVID-19 precautions can help inform hand surgeons on areas for continued patient education.

Atmospheric modelling of grass pollen rupturing mechanisms for thunderstorm asthma prediction.

The world's most severe thunderstorm asthma event occurred in Melbourne, Australia on 21 November 2016, coinciding with the peak of the grass pollen season. The aetiological role of thunderstorms in these events is thought to cause pollen to rupture in high humidity conditions, releasing large numbers of sub-pollen particles (SPPs) with sizes very easily inhaled deep into the lungs. The humidity hypothesis was implemented into a three-dimensional atmospheric model and driven by inputs from three meteorological models. However, the mechanism could not explain how the Melbourne event occurred as relative humidity was very low throughout the atmosphere, and most available grass pollen remained within 40 m of the surface. Our tests showed humidity induced rupturing occurred frequently at other times and would likely lead to recurrent false alarms if used in a predictive capacity. We used the model to investigate a range of other possible pollen rupturing mechanisms which could have produced high concentrations of SPPs in the atmosphere during the storm. The mechanisms studied involve mechanical friction from wind gusts, electrical build up and discharge incurred during conditions of low relative humidity, and lightning strikes. Our results suggest that these mechanisms likely operated in tandem with one another, but the lightning method was the only mechanism to generate a pattern in SPPs following the path of the storm. If humidity induced rupturing cannot explain the 2016 Melbourne event, then new targeted laboratory studies of alternative pollen rupture mechanisms would be of considerable value to help constrain the parameterisation of the pollen rupturing process.

Microarray background correction: maximum likelihood estimation for the normal-exponential convolution.

Background correction is an important preprocessing step for microarray data that attempts to adjust the data for the ambient intensity surrounding each feature. The "normexp" method models the observed pixel intensities as the sum of 2 random variables, one normally distributed and the other exponentially distributed, representing background noise and signal, respectively. Using a saddle-point approximation, Ritchie and others (2007) found normexp to be the best background correction method for 2-color microarray data. This article develops the normexp method further by improving the estimation of the parameters. A complete mathematical development is given of the normexp model and the associated saddle-point approximation. Some subtle numerical programming issues are solved which caused the original normexp method to fail occasionally when applied to unusual data sets. A practical and reliable algorithm is developed for exact maximum likelihood estimation (MLE) using high-quality optimization software and using the saddle-point estimates as starting values. "MLE" is shown to outperform heuristic estimators proposed by other authors, both in terms of estimation accuracy and in terms of performance on real data. The saddle-point approximation is an adequate replacement in most practical situations. The performance of normexp for assessing differential expression is improved by adding a small offset to the corrected intensities.

Estimating haplotype effects for survival data.

Genetic association studies often investigate the effect of haplotypes on an outcome of interest. Haplotypes are not observed directly, and this complicates the inclusion of such effects in survival models. We describe a new estimating equations approach for Cox's regression model to assess haplotype effects for survival data. These estimating equations are simple to implement and avoid the use of the EM algorithm, which may be slow in the context of the semiparametric Cox model with incomplete covariate information. These estimating equations also lead to easily computable, direct estimators of standard errors, and thus overcome some of the difficulty in obtaining variance estimators based on the EM algorithm in this setting. We also develop an easily implemented goodness-of-fit procedure for Cox's regression model including haplotype effects. Finally, we apply the procedures presented in this article to investigate possible haplotype effects of the PAF-receptor on cardiovascular events in patients with coronary artery disease, and compare our results to those based on the EM algorithm.

Is the Kaiser Permanente model superior in terms of clinical integration?: a comparative study of Kaiser Permanente, Northern California and the Danish healthcare system.

BACKGROUND: Integration of medical care across clinicians and settings could enhance the quality of care for patients. To date, there is limited data on the levels of integration in practice. Our objective was to compare primary care clinicians' perceptions of clinical integration and three sub-aspects in two healthcare systems: Kaiser Permanente, Northern California (KPNC) and the Danish healthcare system (DHS). Further, we examined the associations between specific organizational factors and clinical integration within each system. METHODS: Comparable questionnaires were sent to a random sample of primary care clinicians in KPNC (n = 1103) and general practitioners in DHS (n = 700). Data were analysed using multiple logistic regression models. RESULTS: More clinicians in KPNC perceived to be part of a clinical integrated environment than did general practitioners in the DHS (OR = 3.06, 95% CI: 2.28, 4.12). Further, more KPNC clinicians reported timeliness of information transfer (OR = 2.25, 95% CI: 1.62, 3.13), agreement on roles and responsibilities (OR = 1.79, 95% CI: 1.30, 2.47) and established coordination mechanisms in place to ensure effective handoffs (OR = 6.80, 95% CI: 4.60, 10.06). None of the considered organizational factors in the sub-country analysis explained a substantial proportion of the variation in clinical integration. CONCLUSIONS: More primary care clinicians in KPNC reported clinical integration than did general practitioners in the DHS. Focused measures of clinical integration are needed to develop the field of clinical integration and to create the scientific foundation to guide managers searching for evidence based approaches.

Septic Arthritis of the Pediatric Wrist: A Case Report and Review of the Literature.

Septic arthritis of the wrist in pediatric patients is a rare diagnosis and is not well described in the literature. We present a case of a 4-month old patient with monoarticular septic arthritis of the wrist treated with surgical drainage and antibiotics. Although a rare diagnosis, septic arthritis of the wrist should be considered in patients with pseudoparalysis of the upper extremity and systemic signs of inflammation. Prompt diagnosis and treatment is critical to prevent permanent damage to the joint. Further data is needed to describe the epidemiology, microbiology, diagnostic findings and treatment of septic arthritis of the pediatric wrist.

Using crowd-sourced allergic rhinitis symptom data to improve grass pollen forecasts and predict individual symptoms.

Seasonal allergic rhinitis (AR), also known as hay fever, is a common respiratory condition brought on by a range of environmental triggers. Previous work has characterised the relationships between community-level AR symptoms collected using mobile apps in two Australian cities, Canberra and Melbourne, and various environmental covariates including pollen. Here, we build on these relationships by assessing the skill of models that provide a next-day forecast of an individual's risk of developing AR and that nowcast ambient grass pollen concentrations using crowd-sourced AR symptoms as a predictor. Categorical grass pollen forecasts (low/moderate/high) were made based on binning mean daily symptom scores by corresponding categories. Models for an individual's risk were constructed by forward variable selection, considering environmental, demographic, behaviour and health-related inputs, with non-linear responses permitted. Proportional-odds logistic regression was then applied with the variables selected, modelling the symptom scores on their original five-point scale. AR symptom-based estimates of today's average grass pollen concentration were more accurate than those provided by two benchmark forecasting methods using various metrics for assessing accuracy. Predictions of an individual's next-day AR symptoms rated on a five-point scale were correct in 36% of cases and within one point on this scale in 82% of cases. Both outcomes were significantly better than chance. This large-scale AR symptoms measurement program shows that crowd-sourced symptom scores can be used to predict the daily average grass pollen concentration, as well as provide a personalised AR forecast.

Crowd-sourced allergic rhinitis symptom data: The influence of environmental and demographic factors.

Allergic Rhinitis (AR) affects over half a billion people worldwide with an estimated prevalence of 1 in 5 individuals in developed countries. Although ambient pollen exposure is a causal factor in AR, the symptom-exposure relationship is typically not studied in the broader community but in small, well-characterised cohorts drawn from clinical populations. To identify relationships between AR symptoms in the community and a range of environmental factors, we used a database containing over 96,000 symptom score reports collected over a 3-year period (2014-2016) through freely available smartphone apps released in two Australian cities, Melbourne and Canberra. Ambient pollen levels and symptom scores were strongly related, with grass pollen explaining most of the symptom variation. Other factors correlated with higher symptom scores included temperature (R > 0.73) and wind speed (R > 0.75). In general, worse symptom scores were reported by younger participants, women, and those who had taken medication for AR in the preceding 24 h. The strength of this relationship varied between the two cities. Smartphone-based symptom surveys offer a cost-effective means of studying real-world risk factors for AR in a broader 'extra-clinical' population.

Are convergence lines associated with high asthma presentation days? A case-control study in Melbourne, Australia.

BACKGROUND: In epidemic thunderstorm asthma (ETSA) events a large number of people develop asthma symptoms over a short period of time. This is thought to occur because of a unique combination of high amounts of pollen and certain meteorological conditions. However, the exact cause and mechanism of epidemic thunderstorm asthma remains unclear. OBJECTIVES: The objective of this study was to test the hypothesis that convergence lines may be a causative factor in ETSA events, by investigating whether convergence line weather events are associated with the occurrence of high asthma presentations days during the Victorian grass pollen season (October-December). METHODS: A case control method was used. All public hospitals within 75 km of the Melbourne weather radar were included, and data were taken from 2009 to 2017 during the Victorian grass pollen season. Cases hospital days were hospitals with a high number of asthma presentations within a 24-h period, and controls were hospitals with an expected number of asthma presentations. Exposure was defined as geographical proximity of a convergence line to the hospital case or control. RESULTS: Eighty-one case hospital days and 157 hospital day controls were included in the study. The odds of exposure to a convergence line were significantly higher for cases than for controls at all exposure distances. At 4 km, 80 of the 81 cases had been exposed to a convergence line. CONCLUSION: Convergence lines appear to be a necessary, but not sufficient, element in the cause of epidemic thunderstorm asthma. This is the first study to show a clear link between epidemic thunderstorm asthma and convergence lines.