COVID-19 severity in asthma patients: a multi-center matched cohort study.

OBJECTIVE: The evidence pertaining to the effects of asthma on Coronavirus disease 2019 outcomes has been unclear. To improve our understanding of the clinically important association of asthma and Coronavirus disease 2019. METHODS: A matched cohort study was performed using data from the Mass General Brigham Health Care System (Boston, MA). Adult (age ≥18 years) patients with confirmed Coronavirus disease 2019 and without chronic obstructive pulmonary disease, cystic fibrosis, or interstitial lung disease between March 4, 2020 and July 2, 2020 were analyzed. Up to five non-asthma comparators were matched to each asthma patient based on age (within 5 years), sex, and date of positive test (within 7 days). The primary outcomes were hospitalization, mechanical ventilation, and death, using multivariable Cox-proportional hazards models accounting for competing risk of death, when appropriate. Patients were followed for these outcomes from diagnosis of Coronavirus disease 2019 until July 2, 2020. RESULTS: Among 562 asthma patients, 199 (21%) were hospitalized, 15 (3%) received mechanical ventilation, and 7 (1%) died. Among the 2686 matched comparators, 487 (18%) were hospitalized, 107 (4%) received mechanical ventilation, and 69 (3%) died. The adjusted Hazard Ratios among asthma patients were 0.99 (95% Confidence Internal 0.80, 1.22) for hospitalization, 0.69 (95% Confidence Internal 0.36, 1.29) for mechanical ventilation, and 0.30 (95% Confidence Internal 0.11, 0.80) for death. CONCLUSIONS: In this matched cohort study from a large Boston-based healthcare system, asthma was associated with comparable risk of hospitalization and mechanical ventilation but a lower risk of mortality.

Sex differences in academic rank in allergy/immunology.

BACKGROUND: Female physicians are significantly less likely than male physicians to be full professors, even after accounting for age, experience, specialty, and measures of research and clinical productivity. OBJECTIVE: We sought to evaluate sex differences in academic rank in the allergy and immunology workforce. METHODS: We used a cross-sectional physician data set containing the allergist's sex, age, years since residency, faculty appointment, authored publications, National Institutes of Health (NIH) funding, clinical trial investigation, and Medicare reimbursement to investigate sex differences in the academic allergy and immunology workforce using multilevel logistic regression models. RESULTS: Among 507 academic allergists (9.3% of practicing US allergists in 2014), 323 (63.7%) were men, and 184 (36.3%) were women. Female allergists were younger (47.9 vs 56.9 years, P < .001), had fewer total (12.5 vs 28.7, P < .001) and first/last author (8.0 vs 21.5, P < .001) average publications, were less likely to have NIH funding (13.0% vs 23.5%, P = .004), were less frequently a clinical trial investigator (10.3% vs 16.1%, P = .07), and generated less average annual Medicare revenue ($44,000 vs $23,000, P = .10). Of 152 (30.0%) full professors, 126 (82.9%) were male, and 26 (17.0%) were female. After multivariable adjustment, rates of full professorship among female and male allergists were not significantly different (absolute adjusted difference for female vs male allergists, 6.0%; 95% CI, -8.3% to 20.2%). CONCLUSIONS: Among allergists with US medical school faculty appointments, men and women were similarly likely to be full professors after accounting for factors influencing promotion. Underlying differences in research productivity and NIH funding not explained by age differences alone warrant additional investigation.

Mining social media data to assess the risk of skin and soft tissue infections from allergen immunotherapy.

BACKGROUND: Allergen immunotherapy (AIT) treatment for allergic rhinitis and asthma is used by 2.6 million Americans annually. Clinical and sterility testing studies identify no risk of contamination or infection from extracts prepared using recommended aseptic techniques, but regulatory concerns persist. Social media can be used to investigate rare adverse effects not captured by traditional studies. OBJECTIVE: We sought to investigate large social media databases for suggestion of AIT skin and soft tissue infection (SSTI) risk and compare this risk to a comparator procedure with a sterile pharmaceutical. METHODS: We analyzed US-restricted data from more than 10 common text-based social media platforms including Facebook, Twitter, and Reddit between 2012 and 2016. We used natural language processing (NLP) to identify posts related to AIT and, separately, influenza vaccination (comparator procedure). NLP was followed by manual review to identify posts suggesting a possible SSTI associated with either AIT or influenza vaccination. SSTI frequencies with 95% CIs were compared. RESULTS: We identified 25,126 AIT posts, which were matched by social media platform to 25,126 influenza vaccination-related posts. NLP identified 4088 (16.3%) AIT posts that required manual review, with 6 posts (0.02%; 95% CI, 0.005%-0.043%) indicative of possible AIT-related SSTI. NLP identified 2689 (10.7%) influenza posts that required manual review, with 7 posts (0.03%; 95% CI, 0.007%-0.048%) indicative of possible influenza vaccination-related SSTI. CONCLUSIONS: Social media data suggest that SSTI from AIT and influenza vaccination are equally rare events. Given that AIT's SSTI risk appears comparable to the risk using a sterile pharmaceutical based on social media data, current aseptic technique procedures seem safe.

Prevalence of rheumatic heart disease in Zambian school children.

BACKGROUND: The large global burden of rheumatic heart disease (RHD) has come to light in recent years following robust epidemiologic studies. As an operational research component of a broad program aimed at primary and secondary prevention of RHD, we sought to determine the current prevalence of RHD in the country's capital, Lusaka, using a modern imaging-based screening methodology. In addition, we wished to evaluate the practicality of training local radiographers in echocardiography screening methods. METHODS: Echocardiography was conducted on a random sample of students in 15 schools utilizing a previously validated, abbreviated screening protocol. Through a task-shifting scheme, and in the spirit of capacity-building to enhance local diagnostic and research skills, general radiographers based at Lusaka University Teaching Hospital (UTH) were newly trained to use portable echocardiography devices. Students deemed as screen-positive were referred for comprehensive echocardiography and clinical examination at UTH. Cardiac abnormalities were classified according to standard World Heart Federation criteria. RESULTS: Of 1102 students that were consented and screened, 53 students were referred for confirmatory echocardiography. Three students had definite RHD, 10 had borderline RHD, 29 were normal, and 11 students were lost to follow-up. The rates of definite, borderline, and total RHD were 2.7 per 1000, 9.1 per 1000, and 11.8 per 1000, respectively. Anterior mitral valve leaflet thickening and chordal thickening were the most common morphological defects. The pairwise kappa test showed fair agreement between the local radiographers and an echocardiographer quality assurance specialist. CONCLUSION: The prevalence of asymptomatic RHD in urban communities in Zambia is within the range of results reported in other sub-Saharan African countries using the WHF criteria. Task-shifting local radiographers to conduct echocardiography was feasible. The results of this study will be used to inform ongoing efforts in Zambia to control and eventually eliminate RHD. TRIAL REGISTRATION: The study was registered on clinicaltrials.gov ( #NCT02661763 ).

Cardiovascular and cerebrovascular events among patients receiving omalizumab: Results from EXCELS, a prospective cohort study in moderate to severe asthma.

BACKGROUND: EXCELS, a postmarketing observational cohort study, was a commitment to the US Food and Drug Administration to assess the long-term safety of omalizumab in an observational setting, focusing predominantly on malignancies. OBJECTIVE: The aim of this study was to examine a potential association between omalizumab and cardiovascular (CV)/cerebrovascular (CBV) events in EXCELS. METHODS: Patients (≥12 years of age) with moderate to severe allergic asthma and who were being treated with omalizumab (n = 5007) or not (n = 2829) at baseline were followed up for ≤5 years. Analyses included overall CV/CBV events, but focused on the subset of arterial thromboembolic events (ATEs), comprising CV death, myocardial infarction, ischemic stroke, transient ischemic attack, and unstable angina. A prespecified analysis of the end point of ATE was conducted to control for available potential confounders. A blinded independent expert panel adjudicated all events. RESULTS: At baseline, the 2 cohorts had similar demographic characteristics, but severe asthma was more common in the omalizumab versus the non-omalizumab group (50% vs 23%). Omalizumab-treated patients had a higher rate of CV/CBV serious adverse events (13.4 per 1,000 person years [PYs]) than did non-omalizumab-treated patients (8.1 per 1,000 PYs). The ATE rates per 1,000 PYs were 6.66 (101 patients/15,160 PYs) in the omalizumab cohort and 4.64 (46 patients/9,904 PYs) in the non-omalizumab cohort. After control for available confounding factors, the hazard ratio was 1.32 (95% CI, 0.91-1.91). CONCLUSION: This observational study demonstrated a higher incidence rate of CV/CBV events in the omalizumab versus the non-omalizumab cohort. Differences in asthma severity between cohorts likely contributed to this imbalance, but some increase in risk cannot be excluded.

Immune-mediated reactions to vancomycin: A systematic case review and analysis.

BACKGROUND: Vancomycin is a broad-spectrum antibiotic whose use may be limited by adverse drug reactions (ADRs). Although vancomycin toxic effects are known, there are limited data on vancomycin hypersensitivity reactions (HSRs). OBJECTIVE: To understand the most commonly reported vancomycin HSRs through systematic case review. METHODS: We performed a literature search for English-language case reports and series from 1982 through 2015 (last search July 31, 2015) on Ovid MEDLINE and PubMed. The search included the subject heading vancomycin with the subheading adverse effects and separate text searches for vancomycin with a list of specified HSRs. References of identified articles were reviewed to find additional articles. Clinical data were collected and summarized. RESULTS: Of 201 identified articles, 84 were screened and 57 fully assessed; these 57 articles contained 71 vancomycin HSR cases that were included in analysis. Vancomycin HSRs were immediate (anaphylaxis, n = 7) and nonimmediate (n = 64). Nonimmediate HSRs included linear IgA bullous dermatosis (LABD, n = 34), drug rash eosinophilia and systemic symptoms (DRESS) syndrome (n = 16), acute interstitial nephritis (AIN, n = 8), and Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN, n = 6). Median times of vancomycin therapy before HSR onset was 7 days (interquartile range [IQR], 4-10 days) for LABD, 9 days (IQR, 9-22 days) for SJS/TEN, 21 days (IQR, 17-28 days) for DRESS syndrome, and 26 days (IQR, 7-29 days) for AIN. Overall, 11 patients (16%) died, and 4 (6%) had deaths attributed to the HSR. CONCLUSION: Vancomycin causes a variety of HSRs; the most commonly identified were nonimmediate HSRs, with LABD being most frequent. We observed a high frequency of HSR mortality. Further data are needed to understand the frequency and severity of vancomycin HSRs.

Risk-stratification protocol for carboplatin and oxaliplatin hypersensitivity: repeat skin testing to identify drug allergy.

BACKGROUND: Hypersensitivity reactions (HSRs) to platinum-based chemotherapies are increasingly being recognized. The authors developed a novel risk-stratification protocol that was used successfully in a small number of patients with carboplatin-induced HSRs. OBJECTIVE: To describe the utility of this protocol in a large number of patients with carboplatin- or oxaliplatin-induced HSRs. METHODS: A 5-year retrospective review of patients referred to Massachusetts General Hospital with carboplatin- or oxaliplatin-induced HSR was performed. Patients were managed using a risk-stratification protocol using 3 repeat skin tests (STs) with intervening desensitizations. If the repeat ST result remained negative 3 times, patients received subsequent infusions without desensitization. RESULTS: From 2008 to 2012, 142 patients (92 treated with carboplatin, 50 treated with oxaliplatin) completed 574 desensitizations. Most patients were women (84.5%, mean ± SD 58.1 ± 9.3 years). Patients with carboplatin-induced HSRs were classified as having positive (n = 32, 34.8%), negative (n = 38, 41.3%), or converted (n = 22, 23.9%) ST reactions when the initial negative ST reaction converted to positive at repeat ST. Of those with oxaliplatin-induced HSRs, 22 (44%) had positive, 25 (50%) had negative, and 3 (6%) had converted ST reactions. Of the patients with negative ST reactions, 17 with carboplatin-induced HSRs and 16 with oxaliplatin-induced HSRs safely completed 59 and 95 outpatient infusions, respectively, without desensitizations. For carboplatin and oxaliplatin, ST conversion was associated with an interval of at least 6 months from the HSR to the initial ST (carboplatin, P = .002; oxaliplatin, P = .045). CONCLUSION: This risk-stratification protocol for presumed carboplatin- and oxaliplatin-induced HSRs safely identifies false-negative ST reactions and nonallergic patients who can receive infusions without desensitizations. This leads to fewer unnecessary desensitizations and improved patient care.

Incidence of malignancy in patients with moderate-to-severe asthma treated with or without omalizumab.

BACKGROUND: The Epidemiologic Study of Xolair (omalizumab): Evaluating Clinical Effectiveness and Long-term Safety in Patients with Moderate-to-Severe Asthma (EXCELS) assessed the long-term safety of omalizumab in a clinical practice setting as part of a phase IV US Food and Drug Administration postmarketing commitment. OBJECTIVE: We sought to evaluate long-term safety in omalizumab-treated and nonomalizumab-treated patients. Primary outcome measures focused on assessment of malignancies. METHODS: EXCELS was a prospective observational cohort study in patients (≥12 years of age) with moderate-to-severe allergic asthma. There were 2 cohorts: omalizumab (taking omalizumab at baseline) and nonomalizumab (no history of omalizumab treatment). Primary outcomes included all confirmed, incident, study-emergent primary malignancies (malignancies), including and excluding nonmelanoma skin cancer (NMSC); all malignancies were externally adjudicated. RESULTS: The omalizumab cohort had a higher proportion of patients with severe asthma compared with the nonomalizumab cohort (50.0% vs 23.0%). Median follow-up was approximately 5 years for both cohorts. Crude malignancy rates were similar in the omalizumab and nonomalizumab cohorts, with a rate ratio of 0.84 (95% CI, 0.62-1.13) for all malignancies and 0.98 (95% CI, 0.71-1.36) for all malignancies excluding NMSC. Kaplan-Meier plots of time to first confirmed study-emergent primary malignancy were similar for the 2 treatment cohorts. Cox proportional hazards modeling, adjusting for confounders and risk factors, resulted in a hazard ratio (omalizumab vs nonomalizumab) of 1.09 (95% CI, 0.87-1.38) for all malignancies and 1.15 (95% CI, 0.83-1.59) for all malignancies excluding NMSC. CONCLUSION: Results from EXCELS suggest that omalizumab therapy is not associated with an increased risk of malignancy.

Evaluation and management of hypersensitivity to proton pump inhibitors.

OBJECTIVE: Proton pump inhibitors (PPIs) are widely used for the treatment of gastroesophageal reflux disease and peptic ulcer disease. PPIs are well tolerated, but they can cause hypersensitivity reactions (HSRs). Although simply avoiding a PPI after an HSR is appropriate for most patients, there are clinical scenarios that require treatment with a PPI. DATA SOURCES: A comprehensive literature review was performed to propose an evidence-based approach to the evaluation and management of HSRs to PPIs. STUDY SELECTIONS: Articles from June 1986 through September 2012 on PPI hypersensitivity were reviewed. Thirty-nine studies that met the search criteria were included in the review. HSRs to PPIs and skin testing protocols used to evaluate HSRs were analyzed from the 39 identified publications. For each case, the culprit drug and dose, the age and sex of the patient, and the symptoms and timing of the HSR were recorded. HSRs were classified into immune- or nonimmune-mediated categories. RESULTS: A total of 118 cases of immune-mediated HSRs to 5 PPIs were identified, most of which were suspected IgE-mediated HSRs. Omeprazole was the culprit PPI most frequently associated with HSRs. The most common clinical manifestations of PPI HSRs were cutaneous reactions. Nonirritating concentrations for skin prick and intradermal testing were identified. Skin testing showed variable cross-reactivity patterns among the different PPIs. CONCLUSION: The HSRs to PPIs should be formally investigated, especially when reasonable alternative therapies do not exist. The reviewers propose an evidence-based algorithm for evaluating and managing patients with an HSR to a PPI.

A protocol for risk stratification of patients with carboplatin-induced hypersensitivity reactions.

BACKGROUND: Management of patients with carboplatin-induced hypersensitivity reactions (HSR) has been complicated by high false-negative rates of carboplatin skin test (ST) results. These patients might be at risk for future carboplatin-induced HSRs. In this article we identify a strategy to improve risk stratification of patients with a history of carboplatin-induced HSRs by using a protocol that includes repeat skin testing and drug desensitization. OBJECTIVE: We sought to identify a management strategy for patients with a history of carboplatin-induced HSRs with negative carboplatin ST results. METHODS: From 2008-2010, patients with carboplatin-induced HSR underwent risk stratification per a protocol using 3 repeat STs with intervening drug desensitizations. RESULTS: Of the 44 patients with carboplatin-induced HSRs, 39 completed the protocol. Patients were classified as having positive ST results (n = 16), having negative ST results (n = 11), or ST converters when the ST result converted to positive after an initial negative result (n = 12). ST converters are more likely to have HSRs during subsequent desensitizations than patients with negative ST results (56.1% vs 4.5%, P < .001). ST converters had a significantly longer time interval between their initial HSR and initial ST evaluation compared with either patients with true-negative ST results (22.1 vs 6.0 months, P = .03) or patients with positive ST results (22.1 vs 1.8 months, P = .001). CONCLUSION: Our experience suggests that repeat STs are necessary for risk stratification in patients with a remote clinical history of HSR and an initial negative ST result because there is a significant rate of conversion to a positive ST result. ST converters have an increased risk of HSRs during subsequent carboplatin treatment.

Difficult asthma: assessment and management, Part 1.

A minority of asthma patients have disease that proves difficult to control with usual medications and experience ongoing symptoms, poor quality of life, and limitations in activity and/or frequent asthma exacerbations. This group of patients accounts for much of the expense associated with asthma care and is the focus of national and international collaborative study groups. Distinguishing between "difficult-to-manage asthma" and truly "therapy-resistant asthma" is helpful and promotes a systematic consideration of contributory factors. Critical evaluation of factors contributing to difficult-to-manage asthma including adverse environment, comorbidities, nonadherence, and incorrect diagnosis is recommended in a systematic fashion in Part 1 of this contribution.

Difficult asthma: assessment and management, Part 2.

Patients with severe asthma have considerable morbidity related to their asthma and are at risk for serious, life-threatening exacerbations. Their management requires an intensive and comprehensive approach, including attention to reducing exposure to environmental inciters of airway inflammation and triggers of symptoms, patient education (including an asthma action plan), and opportunity for close patient-provider communication. Approved medical options include the lipoxygenase inhibitor, zileuton; the anti-immunoglobulin E monoclonal antibody, omalizumab; and bronchial thermoplasty. Nonapproved interventions of potential benefit are ultrahigh-dose inhaled corticosteroids, anticholinergic bronchodilators (tiotropium), macrolide antibiotics, and vitamin D supplementation for the vitamin D-deficient patient. Potentially toxic, "steroid-sparing" therapies such as methotrexate, cyclosporine, and etanercept are best reserved for patients participating in clinical trials. Recognition of specific subtypes of patients with therapy-resistant asthma permits more targeted treatment approaches, such as for aspirin-sensitive asthma, persistent eosinophilic asthma, asthma complicated by allergic bronchopulmonary aspergillosis, asthma with persistent airflow obstruction, and asthma with life-threatening (near fatal) asthmatic attacks. Novel therapies based on an improved understanding of the pathobiology of therapy-resistant asthma are greatly needed.

The importance of vancomycin in drug rash with eosinophilia and systemic symptoms (DRESS) syndrome.

Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome characterized by fever, rash, eosinophilia, atypical lymphocytes, and multiorgan involvement has a significant mortality. Inpatient vancomycin use is increasing and appears to be emerging as an important etiology of DRESS syndrome. This study highlights the importance of vancomycin as a cause of DRESS syndrome. We reviewed all cases of DRESS syndrome among inpatients consulted by the Allergy & Immunology service at Massachusetts General Hospital (MGH) from July 2009 through December 2010. We also reviewed the use of inpatient parenteral vancomycin over the past 4 years at MGH. Six patients fulfilled clinical criteria for DRESS syndrome, including rash, fever, eosinophilia, and hepatitis, with five (83%) having vancomycin as the attributable cause. Onset of symptoms varied from 12 days to 4 weeks after start of vancomycin treatment. Systemic findings included atypical lymphocytes, lymphadenopathy, nephritis, hypotension, tachycardia, and pharyngitis. Treatment with corticosteroids was required in three cases. Recurrence of peripheral eosinophilia was a marker of disease relapse. In three of the five patients (60%), elevated human herpesvirus 6 (HHV6) IgG titers correlated with greater systemic involvement and prolonged time to resolution. MGH pharmacy records indicate a progressive increase in the number of patients treated with parenteral vancomycin over the last 4 years. Causative agents for DRESS syndrome in an inpatient setting is likely different from that seen in the general population. With increasing use of vancomycin, we are likely to see more cases of DRESS syndrome caused by vancomycin. Recognition of vancomycin as a common cause of inpatient DRESS syndrome is important.

Lifetime Allergy Symptoms in IgG4-Related Disease: A Case-Control Study.

OBJECTIVE: The etiology of IgG4-related disease (IgG4-RD) is unknown, and there has been controversy over the significance of allergic conditions in IgG4-RD. We examined the prevalence of lifetime allergy symptoms in IgG4-RD and the association between these and IgG4-RD. METHODS: We identified IgG4-RD patients and non-IgG4-RD controls without autoimmune conditions seen at a single center. IgG4-RD patients were classified using the American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria. Allergy symptoms were ascertained by questionnaire. We assessed the association of IgG4-RD features with allergy symptoms. We compared the proportion of cases and controls with allergy symptoms using conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) after matching cases and controls 1:1 by age and sex. RESULTS: Lifetime allergy symptoms were reported by 165 (71%) of 231 IgG4-RD patients. Aeroallergen symptoms were most commonly reported (n = 135, 58%), followed by skin allergy symptoms (n = 97, 42%) and food allergy symptoms (n = 47, 20%). IgG4-RD cases with a history of allergy symptoms were more likely to have head and neck involvement (OR 2.0 [95% CI 1.1-3.6]) and peripheral eosinophilia (OR 3.3 [95% CI 1.2-9.0]) than those without allergy symptoms. The prevalence of any allergy symptoms was similar between cases and controls (OR 0.7 [95% CI 0.4-1.1]); this remained consistent after stratifying by head and neck involvement. CONCLUSION: Lifetime allergy symptoms are common in IgG4-RD but are not reported more often in IgG4-RD compared to non-IgG4-RD patients without autoimmune conditions. These findings suggest that allergies are not uniquely associated with the pathogenesis or presentation of IgG4-RD.

mRNA Vaccines to Prevent COVID-19 Disease and Reported Allergic Reactions: Current Evidence and Suggested Approach.

The U.S. Food and Drug Administration (FDA) has recently issued an Emergency Use Authorization (EUA) for 2 highly effective coronavirus disease 2019 (COVID-19) vaccines from Pfizer-BioNTech and Moderna. This has brought hope to millions of Americans in the midst of an ongoing global pandemic. The FDA EUA guidance for both vaccines is to not administer the vaccine to individuals with a known history of a severe allergic reaction (eg, anaphylaxis) to any component of the COVID-19 vaccine. The Centers for Disease Control and Prevention (CDC) additionally advises individuals with a history of an immediate allergic reaction to a vaccine or injectable or any history of anaphylaxis be observed for 30 minutes after COVID-19 vaccination. All other individuals should be observed for 15 minutes after COVID-19 vaccination. Staff at vaccine clinics must be able to identify and manage anaphylaxis. Post-FDA EUA, despite very strong safety signals in both phase 3 trials, reports of possible allergic reactions have raised public concern. To provide reassurance and support during widespread global vaccination, allergists must offer clear guidance to individuals based on the best information available, but also in accordance with the broader recommendations of regulatory agencies. This review summarizes vaccine allergy epidemiology and proposes drug and vaccine allergy expert opinion informed risk stratification for Allergy specialist use in conjunction with guidance of public health and regulatory authorities. The risk stratification schema guide care for (1) individuals with different allergy histories to safely receive their first mRNA COVID-19 vaccine and (2) individuals who develop a reaction to their first dose of mRNA COVID-19 vaccine.

Subacute lack of asthma control and acute asthma exacerbation history as predictors of subsequent acute asthma exacerbations: evidence from managed care data.

BACKGROUND: Monitoring indicators of subacute lack of asthma control (SALAC) may help to reduce asthma morbidity. OBJECTIVE: To determine whether SALAC, independent of current asthma exacerbations, is associated with subsequent acute asthma exacerbations. METHODS: Administrative claims data from PharMetrics/IMS Health were used to identify patients 12 years or older continuously enrolled in a participating U.S. health plan from 2001 to 2004 with >or=1 asthma claim (International Classification of Diseases, Ninth Revision, Clinical Modification code 493.x), no chronic obstructive pulmonary disease or cystic fibrosis claims, and >or=1 prescription for an asthma medication during 2001-2004. SALAC was defined as more than 4 asthma-related physician visits (or >or=2/quarter) or more than 5 short-acting beta((2))-adrenergic agonist prescriptions during 2001. Effect of asthma control category (Exacerbation Only [EO], SALAC Only [SO], Both Exacerbation and SALAC [Both], Neither Exacerbation nor SALAC [Neither]) in 2001 on acute asthma exacerbations (hospitalization, emergency department visit, or short-term oral corticosteroid use) during 2002-2004 was assessed using logistic regression, adjusting for gender, age, health plan type, and region. RESULTS: Of 11,779 patients, 8% were assigned to the EO group, 26% to SO, 12% to Both, and 54% to Neither in 2001. The incidence of exacerbations in 2002-2004 was higher for Both (61.8%) versus EO (55.0%) and for SO (37.3%) versus Neither (31.9%). The risk of exacerbation in 2002-2004 was increased significantly (p < .0001) for Both (3.394; 95% confidence interval [CI] = 3.009, 3.827), EO (2.503; 95% CI = 2.176, 2.879), and SO (1.277; 95% CI = 1.166, 1.399) versus Neither. CONCLUSION: In this study, the risk of subsequent exacerbation was greatest in patients with both SALAC and acute asthma exacerbations, followed by those with exacerbations only and those with SALAC only. SO identified an additional 26% of asthma patients at increased risk for subsequent exacerbation. The results from this study demonstrate that SALAC indicators and a history of acute asthma exacerbations are independent predictors of future acute asthma exacerbations and highlight the important role of subacute asthma worsening in predicting and preventing future asthma exacerbations.