Histologic and cytologic changes in normal equine joints after injection with 2.5% injectable polyacrylamide hydrogel reveal low-level macrophage-driven foreign body response.

OBJECTIVE: The data presented in this paper are derived from an in vivo study performed to characterize the nature of the synovial integration process of a 2.5% synthetic cross-linked injectable polyacrylamide hydrogel (2.5 iPAAG) injected IA in horses. ANIMALS: 10 healthy horses not suffering from OA or signs of joint disease were administered 50 or 100 mg 2.5 iPAAG in a total of 13 metacarpophalangeal or middle carpal joints. METHODS: Injected joints were examined at 0, 14, 42, and/or 90 days postinjection. Parameters investigated included clinical examination, synoviocentesis, gross pathology, histology, and scanning electron microscopy. RESULTS: All horses remained clinically normal, with no adverse events recorded throughout the study period. Gross postmortem did not reveal any significant findings. Arthrocentesis cytology parameters remained within clinically normal levels throughout the study. Synovial histology demonstrated that cellular infiltration of macrophages, villus hyperplasia, and vascularization were significantly higher in 2.5 iPAAG-injected joints compared to controls. Scanning electron microscopy confirmed that the 2.5 iPAAG demonstrated an extensive tissue integration as a 3-D scaffolding structure with intact cross-linked strands. CLINICAL RELEVANCE: Results confirm that an IA injection of 2.5 iPAAG induces a typical foreign body response that is predominately macrophage driven with no evidence of fibrosis or mineralization. Integration of the gel is evident by 14 days, with no free gel remaining in the joint cavity at this time.

Changes in buprenorphine waivered provider supply after Virginia Medicaid implements the addiction and recovery treatment services program and Medicaid expansion.

BACKGROUND: Shortages of providers authorized to prescribe buprenorphine may limit access to buprenorphine, which studies have shown to be effective in the treatment of opioid use disorder (OUD). OBJECTIVE: To examine whether two state Medicaid policies in Virginia-the Addiction and Recovery Treatment Services (ARTS) program in 2017, and Medicaid expansion in 2019-increased the number of buprenorphine waivered providers (BWP) in Virginia, compared to other southern states in the United States that did not expand Medicaid. METHODS: The study population includes providers authorized to prescribe buprenorphine. We compute the number of BWP per 100,000 people for the study states, overall and for different waiver limits (30, 100 or 275). Using difference-in-difference regression models, we examine changes in BWP rates for Virginia relative to nonexpansion states in the US South between 2015 and 2020. RESULTS: The rate of increase in BWP was higher in Virginia after implementation of ARTS and Medicaid expansion (148 %), compared to southern nonexpansion states over the same time period (115 %). Relative to nonexpansion states in the South, BWP with patient limits of 100 or 275 increased by 7 % in Virginia after ARTS implementation in 2017, and by an additional 22 % after Medicaid expansion in 2019 (p < 0.05 each). CONCLUSIONS: The findings suggest that public policies that expand access to OUD treatment services-including buprenorphine treatment-may also increase the supply of providers authorized to prescribe buprenorphine, helping to alleviate shortages of BWP providers and further increasing access to care.

Rising Racial Disparities in Opioid Mortality and Undertreatment of Opioid Use Disorder and Mental Health Comorbidities in Virginia.

Introduction: There were more than 100,000 fatal drug overdoses in the U.S. in 2021 alone. In recent years, there has been a shift in opioid mortality from predominantly White rural communities to Black urban communities. This study aimed to identify the Virginia communities disproportionately affected by the overdose crisis and to better understand the systemic factors contributing to disparities in opioid mortality. Methods: Using the state all-payer claims database, state mortality records, and census data, we created a multivariate model to examine the community-level factors contributing to racial disparities in opioid mortality. We used generalized linear mixed models to examine the associations between socioecologic factors and fatal opioid overdoses, opioid use disorder diagnoses, opioid-related emergency department visits, and mental health diagnoses. Results: Between 2015 and 2020, racial disparities in mortality widened. In 2020, Black males were 1.5 times more likely to die of an opioid overdose than White males (47.3 vs 31.6 per 100,000; p<0.001). The rate of mental health disorders strongly correlated with mortality (ß=0.53, p<0.001). Black individuals are not more likely to be diagnosed with opioid use disorder (ß=0.01, p=0.002) or with mental health disorders (ß= -0.12, p<0.001), despite higher fatal opioid overdoses. Conclusions: There are widening racial disparities in opioid mortality. Untreated mental health disorders are a major risk factor for opioid mortality. Findings show pathways to address inequities, including early linkage to care for mental health and opioid use disorders. This analysis shows the use of comprehensive socioecologic data to identify the precursors to fatal overdoses, which could allow earlier intervention and reallocation of resources in high-risk communities.

Associations Between Patient-Reported Experiences with Opioid Use Disorder Treatment and Unmet Treatment Needs and Discontinuation Among Virginia Medicaid Members.

BACKGROUND: Many payers, including Medicaid, the largest payer of opioid use disorder (OUD) treatment, are pursuing treatment-related quality improvement initiatives. Yet, how patient-reported experiences with OUD treatment relate to patient-centered outcomes remains poorly understood. AIM: To examine associations between Medicaid members' OUD treatment experiences, outpatient treatment settings, demographic and social factors, and members' self-report of unmet needs during treatment and treatment discontinuation. METHODS: A sample of Virginia Medicaid members aged 21 years or older with OUD diagnoses who received outpatient OUD treatment completed a mail survey between January 2020 and August 2021 (n = 1042, weighted n = 9244). A treatment experience index was constructed from responses to four items from the Consumer Assessment of Healthcare Providers and Systems (CAHPS) relating to feelings of involvement, safety, and respect and having treatment explained in an understandable way; two additional CAHPS items: "given options for treatment" and "able to refuse treatment" were also assessed. Weighted imputed logistic regressions tested adjusted associations between members' treatment experiences, demographic and social factors, and two outcomes capturing unmet needs during treatment and treatment discontinuation. RESULTS: More positive scores on the treatment experiences index were associated with lower adjusted odds of reporting unmet needs during treatment (aOR: 0.52, 95% CI: 0.41-0.66) and discontinuation (aOR: 0.63, 95% CI: 0.47-0.79). Respondents with serious psychological distress had higher odds of reporting unmet needs during treatment (aOR: 1.69 95% CI: 1.14-2.51) and discontinuation (aOR: 1.84, 95% CI: 1.21-2.82), as did individuals with housing insecurity (unmet needs: (aOR: 1.65, 95% CI: 1.11-2.44); treatment discontinuation: (aOR: 1.56, 95% CI: 1.04-2.36)). CONCLUSION: Using a first-of-its-kind survey of Medicaid members with OUD, we found that members who had more positive treatment experiences were less likely to report unmet treatment needs and discontinue treatment. Care approaches focused on improving patient experience are critical to delivering effective, high-quality OUD treatment.

Adjusting 1.5 degree C climate change mitigation pathways in light of adverse new information.

Understanding how 1.5 °C pathways could adjust in light of new adverse information, such as a reduced 1.5 °C carbon budget, or slower-than-expected low-carbon technology deployment, is critical for planning resilient pathways. We use an integrated assessment model to explore potential pathway adjustments starting in 2025 and 2030, following the arrival of new information. The 1.5 °C target remains achievable in the model, in light of some adverse information, provided a broad portfolio of technologies and measures is still available. If multiple pieces of adverse information arrive simultaneously, average annual emissions reductions near 3 GtCO2/yr for the first five years following the pathway adjustment, compared to 2 GtCO2/yr in 2020 when the Covid-19 pandemic began. Moreover, in these scenarios of multiple simultaneous adverse information, by 2050 mitigation costs are 4-5 times as high as a no adverse information scenario, highlighting the criticality of developing a wide range of mitigation options, including energy demand reduction options.

Computed tomography rates in pediatric trauma patients among emergency medicine and pediatric emergency medicine physicians.

BACKGROUND: Pediatric trauma patients undergo fewer computed tomography (CT) scans when evaluated at pediatric trauma centers (PTC) versus adult trauma centers (ATC) with no change in clinical outcome. Factors contributing to this difference are unclear. We sought to identify whether the training background of physicians, specifically emergency medicine (EM) versus pediatric emergency medicine (PEM), affected the CT rate of pediatric trauma patients within one institution. METHODS: A single-center retrospective study of CT utilization based on attending physicians' training in trauma patients <18 years between November 2018 and November 2020. Attendings were categorized into two groups: EM residency with no PEM fellowship, or pediatrics/EM residency with PEM fellowship. Primary outcomes measured were the proportion of patients receiving a CT and CT positivity rate. RESULTS: Of 463 study patients, CTs were obtained in 145/228 (64%) patients by EM, and 130/235 (55%) by PEM (p=.07). CT positivity rate was 21% and 19% in EM and PEM, respectively (p=.46). The mean number of CTs per patient in EM was 2.8 compared to 2.1 in PEM (p<.01), and for patients with an injury severity score (ISS) >15, mean number of CTs per patient increased to 4.9 in EM versus 2.4 in PEM (p=.01). CONCLUSIONS: The mean number of CTs ordered per patient was statistically higher for EM attendings. The differences between CT rates highlight future opportunities for ongoing development of pediatric trauma imaging guidelines and radiation exposure reduction. LEVELS OF EVIDENCE: Retrospective Study, Level III.

Biochemical and structural basis for the pharmacological inhibition of nuclear hormone receptor PPARγ by inverse agonists.

Recent studies have reported that the peroxisome proliferator-activated receptor gamma (PPARγ) pathway is activated in approximately 40% of patients with muscle-invasive bladder cancer. This led us to investigate pharmacological repression of PPARγ as a possible intervention strategy. Here, we characterize PPARγ antagonists and inverse agonists and find that the former behave as silent ligands, whereas inverse agonists (T0070907 and SR10221) repress downstream PPARγ target genes leading to growth inhibition in bladder cancer cell lines. To understand the mechanism, we determined the ternary crystal structure of PPARγ bound to T0070907 and the corepressor (co-R) peptide NCOR1. The structure shows that the AF-2 helix 12 (H12) rearranges to bind inside the ligand-binding domain, where it forms stabilizing interactions with the compound. This dramatic movement in H12 unveils a large interface for co-R binding. In contrast, the crystal structure of PPARγ bound to a SR10221 analog shows more subtle structural differences, where the compound binds and pushes H12 away from the ligand-binding domain to allow co-R binding. Interestingly, we found that both classes of compound promote recruitment of co-R proteins in biochemical assays but with distinct conformational changes in H12. We validate our structural models using both site-directed mutagenesis and chemical probes. Our findings offer new mechanistic insights into pharmacological modulation of PPARγ signaling.

Identifying bright spot communities: Socioecological, workforce, and healthcare delivery factors influencing opioid mortality.

Context: There were 50,000 U.S. opioid overdose deaths in 2019. Millions suffer from opioid addiction. Identifying protective factors for low community opioid mortality may have important implications for addressing the opioid epidemic. This study was funded through the Virginia (VA) Department of Medical Assistance Services (DMAS) through a SUPPORT Act Grant. Objective: To identify "Bright Spot" communities in Virginia with protective factors associated with reduced opioid mortality and morbidity. Study Design: Ecologic study. Dataset: Virginia All Payer Claims Database (APCD), Virginia Department of Health (VDH) statewide medical examiner registry, and American Community Survey (ACS). Time Period: 2016-2019; 2019 data cited here. Population Studied: APCD includes VA residents with medical claims through commercial, Medicaid, and Medicare coverage. VDH data includes fatal drug overdoses. ACS surveys all VA residents. Outcome Measures: Primary outcome: fatal opioid overdoses. Secondary outcomes: emergency room visits for overdoses and opioid-related diagnoses, outpatient diagnoses for opioid-related disorder, prescription rate for opioids, and prescription rate for buprenorphine. Results: Opioid mortality was associated with higher rates of community poverty (r=.38, p<.0001) and disability (r=.52, r<.0001). Opioid mortality was associated with inequality, with higher Gini index associated with higher opioid mortality (r=.23, p<.0001). A higher percentage of black residents was associated with increased fatal opioid overdoses (r=.37, p<.0001) and ED visits for overdoses (r=.30, p<.0001). A higher percentage of white residents correlated with increased outpatient visits for opioid use disorder (r=.24, p<.0001) and higher rates of buprenorphine (r=.34, p<.0001) and opioid prescriptions (r=.31, p <.0001). Conclusions: These findings suggest significant racial disparities in opioid outcomes. Communities with a higher percentage of black residents are more likely to have higher opioid mortality and a lower rate of outpatient treatment. This association may be affected by the time period used in the analysis (2015-2019), as nationally there has been an increasing rate of synthetic opioid deaths in Black communities. These measures have been incorporated into a multivariate analysis to identify Bright Spot communities, which will be discussed during the presentation.

Correction: Teaching From Afar: Development of a Telemedicine Curriculum for Healthcare Workers in Global Settings.

[This corrects the article DOI: 10.7759/cureus.20123.].

Axial and Rotational Malreduction (Golf Club Deformity) in Distal Femur Fractures.

OBJECTIVES: To describe malreduction of supracondylar distal femur fractures stabilized with lateral femoral locking plates and determine whether a mismatch in axial lateral distal femur anatomy and lateral distal femoral plate design contributes to supracondylar distal femoral fracture malreduction. MATERIALS AND METHODS: OTA/AO 33A were simulated in 7 cadaver femurs and fixed with a lateral distal locking femoral plate placed flush to the lateral femoral condyle (group 1). In group 2, the anterior flange of the plate was externally rotated 10 degrees in relation to the lateral condyle. A motion capture system measured translation and rotation of the articular segment as shaft screws were applied, reducing plate to femoral diaphysis. Articular segment movement was compared between groups using paired Student t test, P < 0.05. A large database of 3D scans of 800 femurs was used to define the relationship of the lateral femoral condyle to the lateral cortical surface of the human femur. RESULTS: Malreduction was observed with anatomic plate application results from medial translation (17 mm) and external rotation (12.2 degrees) (group 1). Modifying plate geometry to match lateral femur anatomy (group 2) improved medial translation by 46% and external rotation by 80%. An analysis of the shape of the 800 distal femurs showed that the average posterior anterior inclination is 16.5 degrees. CONCLUSIONS: Anatomic application of distal femoral plates results in significant malreduction. Modifying the plate design to accommodate 10 degrees slope of lateral distal femur results in partial correction of deformity. Future studies should investigate other means of correcting the malalignment, especially considering the 16.5-degree posterior anterior inclination of the condyle.

Unilateral Sacral Fractures Demonstrate Slow Recovery of Patient-Reported Outcomes Irrespective of Treatment.

OBJECTIVES: To report functional outcomes of unilateral sacral fractures treated both operatively and nonoperatively. DESIGN: Prospective, multicenter, observational study. SETTING: Sixteen Level 1 trauma centers. PATIENTS/PARTICIPANTS: Skeletally mature patients with unilateral zone 1 or 2 sacral fractures categorized as displaced nonoperative (DN), displaced operative (DO), nondisplaced nonoperative (NN), and nondisplaced operative (NO). MAIN OUTCOME MEASUREMENTS: Pelvic displacement was documented on injury plain radiographs. Short Musculoskeletal Function Assessment (SMFA) scores were obtained at baseline and at 3, 6, 12, and 24 months after injury. Displacement was defined as greater than 5 mm in any plane at the time of injury. RESULTS: Two hundred eighty-six patients with unilateral sacral fractures were initially enrolled, with a mean age of 40 years and mean injury severity score of 16. One hundred twenty-three patients completed the 2-year follow-up as follows: 29 DN, 30 DO, 47 NN, and 17 NO with 56% loss to follow-up at 2 years. Highest dysfunction was seen at 3 months for all groups with mean SMFA dysfunction scores: 25 DN, 28 DO, 27 NN, and 31 NO. The mean SMFA scores at 2 years for all groups were 13 DN, 12 DO, 17 NN, and 17 NO. CONCLUSIONS: All groups (operative/nonoperative and displaced/nondisplaced) reported worst function 3 months after injury, and all but (DN) continued to recover for 2 years after injury, with peak recovery for DN seen at 1 year. No functional benefit was seen with operative intervention for either displaced or nondisplaced injuries at any time point. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Medicaid participation among practitioners authorized to prescribe buprenorphine.

INTRODUCTION: This study examines Medicaid participation among buprenorphine waivered providers in Virginia in 2019, with a particular focus on the prescribing differences between different physician specialties, nurse practitioners and physicians assistants (NP and PA). METHODS: Secondary data sources include the 2019 DEA list of buprenorphine waivered prescribers, Virginia Medicaid claims for buprenorphine, physician characteristics from the Virginia Department of Health Professions, SAMHSA Behavioral Treatment Services Locator, and area level characteristics. This cross-sectional study is based on a linkage of Medicaid claims data to a list of Virginia practitioners authorized to prescribe buprenorphine in 2019. Using a two-part logistic regression, we assess prescriber license type and local area factors that are associated with: (1) the probability of prescribing buprenorphine to any Medicaid patients in 2019; (2) the number of Medicaid patients treated by each prescriber in 2019. RESULTS: Adjusted odds ratios show that nurse practitioners with buprenorphine waivers are more likely to treat any Medicaid patients compared to physicians (odds ratio (OR), 2.016; p = 0.000). Among prescribers who treated any Medicaid patients, the probability of treating a large number of Medicaid patients was higher among nurse practitioners relative to physicians (OR, 2.869, p = 0.002). Medicaid participation was much higher among prescribers with patient limits of 100 and 275 compared to prescribers with patient limits of 30 (OR, 6.66, p = 0.000 and 29.40, p = 0.000, respectively). CONCLUSIONS: State Medicaid programs have been at the forefront of addressing their state's opioid epidemic, including expanding access to buprenorphine treatment. This study provides evidence that targeted outreach efforts should include NP license types as well as physicians, and is consistent with prior studies showing that NP are especially important in filling treatment gaps for underserved areas and populations.

A Double-Blinded Positive Control Study Comparing the Relative Efficacy of 2.5% Polyacrylamide Hydrogel (PAAG) Against Triamcinolone Acetonide (TA) And Sodium Hyaluronate (HA) in the Management of Middle Carpal Joint Lameness in Racing Thoroughbreds.

The purpose of this prospective double-blinded positive control study was to compare the efficacy of 2.5% polyacrylamide hydrogel (2.5% PAAG) in the management of middle carpal joint lameness in Thoroughbreds against treatments of triamcinolone acetonide (TA) or sodium hyaluronate (HA). A total of 31 flat-racing Thoroughbreds with lameness (grade 1-3/5) localized to the carpus by intra-articular analgesia were selected. Following a radiological assessment of the carpi confirming the absence of fragment/fracture, the horses were randomly assigned for intra-articular treatment with either 2 ml of 2.5% PAAG, 12 mg TA or 20 mg HA (followed by two further intravenous treatments of 40 mg, at weekly intervals in the HA group only), by a treating veterinarian. All horses were rested for 48 hours post-treatment and then re-entered an unaltered training regimen. Subsequent examinations at 2, 4, and 6 weeks were performed by a blinded examining veterinarian for all groups, while horses treated with 2.5% PAAG were monitored for 12 weeks for recurrence of lameness. Significantly more joints treated with 2.5% PAAG were lame free (83%) at 6 weeks compared to TA (27%; P = .007) and to HA (40%; P = .04). There was no significant difference between TA and HA groups at any time. All the joints treated within 2.5% PAAG that were lame free at 6 weeks (10/12) were still lame-free at 12 weeks. In conclusion, treatment with 2.5% PAAG led to statistically superior results compared to TA and HA in the management of selected middle carpal joint lameness in flat-racing Thoroughbreds, with therapeutic effects persisting up to 12 weeks.

Elbow Arthrodesis Surgical Technique.

SUMMARY: Elbow arthrodesis is an uncommon salvage procedure indicated for failed total elbow arthroplasty, segmental bone loss near the elbow, and severe postinfectious or posttraumatic arthritis. This video demonstrates the surgical technique for elbow arthrodesis in a patient with segmental bony defect of the ulna and postinfectious and posttraumatic elbow arthritis after a severe left arm degloving injury with Monteggia fracture dislocation and radial head fracture.

Emergency Department Access During COVID-19: Disparities in Utilization by Race/Ethnicity, Insurance, and Income.

INTRODUCTION: In March 2020, shelter-in-place orders were enacted to attenuate the spread of coronavirus 2019 (COVID-19). Emergency departments (EDs) experienced unexpected and dramatic decreases in patient volume, raising concerns about exacerbating health disparities. METHODS: We queried our electronic health record to describe the overall change in visits to a two-ED healthcare system in Northern California from March-June 2020 compared to 2019. We compared weekly absolute numbers and proportional change in visits focusing on race/ethnicity, insurance, household income, and acuity. We calculated the z-score to identify whether there was a statistically significant difference in proportions between 2020 and 2019. RESULTS: Overall ED volume declined 28% during the study period. The nadir of volume was 52% of 2019 levels and occurred five weeks after a shelter-in-place order was enacted. Patient demographics also shifted. By week 4 (April 5), the proportion of Hispanic patients decreased by 3.3 percentage points (pp) (P = 0.0053) compared to a 6.2 pp increase in White patients (P = 0.000005). The proportion of patients with commercial insurance increased by 11.6 pp, while Medicaid visits decreased by 9.5 pp (P < 0.00001) at the initiation of shelter-in-place orders. For patients from neighborhoods <300% federal poverty levels (FPL), visits were -3.8 pp (P = 0.000046) of baseline compared to +2.9 pp (P = 0.0044) for patients from ZIP codes at >400% FPL the week of the shelter-in-place order. Overall, 2020 evidenced a consistently elevated proportion of high-acuity Emergency Severity Index (ESI) level 1 patients compared to 2019. Increased acuity was also demonstrated by an increase in the admission rate, with a 10.8 pp increase from 2019. Although there was an increased proportion of high-acuity patients, the overall census was decreased. CONCLUSION: Our results demonstrate changing ED utilization patterns circa the shelter-in-place orders. Those from historically vulnerable populations such as Hispanics, those from lower socioeconomic areas, and Medicaid users presented at disproportionately lower rates and numbers than other groups. As the pandemic continues, hospitals should use operations data to monitor utilization patterns by demographic, in addition to clinical indicators. Messaging about availability of emergency care and other services should include vulnerable populations to avoid exacerbating healthcare disparities.

Biomechanics of periprosthetic femur fractures and early weightbearing.

PURPOSE: The incidence of periprosthetic fractures is expected to rise increase by 4.6% every 10 years between 2015 and 2060. There are few large series examining optimal fixation constructs or the influence of early ambulation on outcome. The purpose of this narrative review is to investigate the published biomechanical considerations for periprosthetic fracture fixation, with specific consideration of early postoperative weightbearing. METHODS: A literature review was performed to identify fracture incidences, etiology, and current trends in weightbearing after fixation. Benefits of early weightbearing, current constructs, and biomechanics are reviewed. RESULTS: The limited data available support medical benefits and increased union rates with early mobilization. Optimal fixation constructs are not agreed upon, but mechanical studies suggest that dual implant constructs can support physiologic weightbearing loads. CONCLUSION: Further clinical trials are required to investigate fracture union and hardware complications in dual implant construct.

Teaching From Afar: Development of a Telemedicine Curriculum for Healthcare Workers in Global Settings.

The Stanford Department of Emergency Medicine joined forces with Digital Medic to create educational materials to teach global healthcare providers how to evaluate patients via telemedicine in the setting of COVID-19. Users then asked for additional education on best practices surrounding the use of telemedicine as a communication medium. Here, we describe our experience in the creation of this additional module and provide some basic feedback received from end-users. We scripted, filmed, and edited a video module for this application over the course of 14 weeks. It was subsequently deployed as part of the larger COVID-19 educational program. To date, the course has had over 28,000 participants. Each was asked to take a pre- and post-test to assess the knowledge of telemedicine best practices before and after the video module; 19,412 elected to take the pre-test and 19,364 took the post-test with overall scores of 84% and 95%, respectively. Anecdotal feedback has been positive. Telemedicine systems have proliferated rapidly around the world, but best practices for physician-to-patient interactions have not been similarly disseminated. We conclude that video modules can be used to fill this educational need quickly and economically.

High sensitivity of tropical precipitation to local sea surface temperature.

Precipitation and atmospheric circulation are the coupled processes through which tropical ocean surface temperatures drive global weather and climate1-5. Local sea surface warming tends to increase precipitation, but this local control is difficult to disentangle from remote effects of conditions elsewhere. As an example of such a remote effect, El Niño Southern Oscillation (ENSO) events in the equatorial Pacific Ocean alter precipitation across the tropics. Atmospheric circulations associated with tropical precipitation are predominantly deep, extending up to the tropopause. Shallow atmospheric circulations6-8 affecting the lower troposphere also occur, but the importance of their interaction with precipitation is unclear. Uncertainty in precipitation observations9,10 and limited observations of shallow circulations11 further obstruct our understanding of the ocean's influence on weather and climate. Despite decades of research, persistent biases remain in many numerical model simulations12-18, including excessively wide tropical rainbands14,18, the 'double-intertropical convergence zone problem'12,16,17 and too-weak responses to ENSO15. These biases demonstrate gaps in our understanding, reducing confidence in forecasts and projections. Here we use observations to show that seasonal tropical precipitation has a high sensitivity to local sea surface temperature. Our best observational estimate is an 80 per cent change in precipitation for every gram per kilogram change in the saturation specific humidity (itself a function of the sea surface temperature). This observed sensitivity is higher than in 43 of the 47 climate models studied, and is associated with strong shallow circulations. Models with more realistic (closer to 80%) sensitivity have smaller biases across a wide range of metrics. Our results apply to both temporal and spatial variation, over regions where climatological precipitation is about one millimetre per day or more. Our analyses of multiple independent observations, physical constraints and model data underpin these findings. The spread in model behaviour is further linked to differences in shallow convection, thus providing a focus for accelerated research to improve seasonal forecasts through multidecadal climate projections.