Economic Burden of Acute Gastroenteritis among Members of Integrated Healthcare Delivery System, United States, 2014-2016.

We conducted a large surveillance study among members of an integrated healthcare delivery system in Pacific Northwest of the United States to estimate medical costs attributable to medically attended acute gastroenteritis (MAAGE) on the day care was sought and during 30-day follow-up. We used multivariable regression to compare costs of MAAGE and non-MAAGE cases matched on age, gender, and index time. Differences accounted for confounders, including race, ethnicity, and history of chronic underlying conditions. Analyses included 73,140 MAAGE episodes from adults and 18,617 from children who were Kaiser Permanente Northwest members during 2014-2016. Total costs were higher for MAAGE cases relative to non-MAAGE comparators as were costs on the day care was sought and costs during follow-up. Costs of MAAGE are substantial relative to the cost of usual-care medical services, and much of the burden accrues during short-term follow-up.

Impact of the Early COVID-19 Pandemic on the Number of HIV Preexposure Prophylaxis Uses and the Proportion of Preexposure Prophylaxis Users Receiving Sexually Transmitted Infection Testing Services.

BACKGROUND: With the potential impact of the COVID-19 pandemic on HIV preexposure prophylaxis (PrEP) care management, we assessed the number of PrEP users and sexually transmitted infection (STI) testing-eligible PrEP users, STI testing rates, and prevalence between prepandemic (January 1, 2018-March 31, 2020) and early-pandemic (April 1, 2020-September 30, 2020) periods. METHODS: In this retrospective cohort study, a PrEP user for a given quarter is defined as either a previous PrEP user or a PrEP initiator who has at least 1-day coverage of tenofovir/emtricitabine in the given quarter. The STI testing-eligible PrEP users for a given quarter were defined as those persons whose runout date (previous dispense date + days of tenofovir/emtricitabine supply) was in the given quarter. RESULTS: The quarterly number of PrEP users increased from the first quarter of 2018 to the first quarter of 2020 and then decreased in the second and third quarter of 2020. Among STI testing-eligible PrEP users who had ≤14 days between runout and next refill date, gonorrhea and chlamydia screening testing rates were 95.1% for prepandemic and 93.4% for early pandemic ( P = 0.1011). Among all STI testing-eligible PrEP users who were tested for gonorrhea and chlamydia, gonorrhea prevalence was 6.7% for prepandemic and 5.7% for early pandemic ( P = 0.3096), and chlamydia prevalence was 7.0% for prepandemic and 5.8% for early pandemic ( P = 0.2158). CONCLUSIONS: Although the early COVID-19 pandemic resulted in lower numbers of PrEP users and PrEP initiators, individuals who remained continuous users of PrEP maintained extremely high rates of bacterial STI screening. With high STI prevalence among PrEP users, assessments of PrEP care management are continuously needed.

Incidence, Etiology, and Healthcare Utilization for Acute Gastroenteritis in the Community, United States.

Knowledge of the epidemiology of sporadic acute gastroenteritis (AGE) in the United States is limited. During September 2016-September 2017, we surveyed Kaiser Permanente Northwest members in Oregon and Washington, USA, to collect data on the 30-day prevalence of dually defined AGE and diarrhea disease and related health-seeking behavior; from a subset of participants, we obtained a stool specimen. Using the iterative proportional fitting algorithm with raked weights, we generated AGE prevalence and annualized rate estimates. We detected norovirus, rotavirus, astrovirus, and sapovirus from submitted stool specimens through real-time quantitative reverse transcription PCR (qRT-PCR). We estimated a 30-day prevalence of 10.4% for AGE and 7.6% for diarrhea only; annual rates were 1.27 cases/person/year for AGE and 0.92 cases/person/year for diarrhea only. Of those with AGE, 19% sought medical care. Almost one quarter (22.4%) of stool specimens from those reporting AGE tested positive for ≥1 viral pathogen, compared with 8.2% from those without AGE.

Sexually Transmitted Infection Testing, Prevalence, and Treatment Among Individuals Receiving HIV Preexposure Prophylaxis Within an Integrated Healthcare Delivery System.

BACKGROUND: Initial and follow-up sexually transmitted infection (STI) and human immunodeficiency virus (HIV) testing are recommended when taking HIV preexposure prophylaxis (PrEP). We assessed STI services before and after PrEP initiation among persons 18 years or older. METHODS: We conducted this retrospective cohort study at a US integrated healthcare delivery system. We measured HIV/STI testing rates, STI prevalence and treatment at 3 time points: (1) at PrEP initiation, (2) at 120 days, and (3) at 210 days. RESULTS: Of 685 PrEP initiators, 67.2% continued PrEP use at 120 days and 49.5% at 210 days. Of PrEP users, HIV and STI testing were greater than 85% and greater than 80%, respectively, at all 3 time points. Prevalence for any chlamydia, rectal chlamydia, and any gonorrhea, rectal gonorrhea, or pharyngeal gonorrhea was always high at the 120 days and 210 days (eg, 6.9%, 10.5%, 6.7%, 5.0%, and 5.2%, respectively, at the 120 days for continuous PrEP users). Over 90% of all individuals who tested positive for chlamydia and gonorrhea received antibiotic pharmacy fills within 7 days at 120 and 210 days. Monthly PrEP-related pharmacy cost was about $2259 to $2659. The proportion of the total medical cost that was PrEP-related pharmacy was about 82% for PrEP continuous users. CONCLUSIONS: Although HIV/STI testing rates were high, they can still be improved during HIV PrEP management. High STI prevalence after PrEP initiation in this study suggests that patients taking PrEP are at risk of acquiring an STI. Interventions to improve STI services during PrEP management are continuously needed.

Norovirus and Other Viral Causes of Medically Attended Acute Gastroenteritis Across the Age Spectrum: Results from the Medically Attended Acute Gastroenteritis Study in the United States.

BACKGROUND: Acute gastroenteritis (AGE) causes a substantial burden in the United States, but its etiology frequently remains undetermined. Active surveillance within an integrated healthcare delivery system was used to estimate the prevalence and incidence of medically attended norovirus, rotavirus, sapovirus, and astrovirus. METHODS: Active surveillance was conducted among all enrolled members of Kaiser Permanente Northwest during July 2014-June 2016. An age-stratified, representative sample of AGE-associated medical encounters were recruited to provide a stool specimen to be tested for norovirus, rotavirus, sapovirus, and astrovirus. Medically attended AGE (MAAGE) encounters for a patient occurring within 30 days were grouped into 1 episode, and all-cause MAAGE incidence was calculated. Pathogen- and healthcare setting-specific incidence estimates were calculated using age-stratified bootstrapping. RESULTS: The overall incidence of MAAGE was 40.6 episodes per 1000 person-years (PY), with most episodes requiring no more than outpatient care. Norovirus was the most frequently detected pathogen, with an incidence of 5.5 medically attended episodes per 1000 PY. Incidence of norovirus MAAGE was highest among children aged < 5 years (20.4 episodes per 1000 PY), followed by adults aged ≥ 65 years (4.5 episodes per 1000 PY). Other study pathogens showed similar patterns by age, but lower overall incidence (sapovirus: 2.4 per 1000 PY; astrovirus: 1.3 per 1000 PY; rotavirus: 0.5 per 1000 PY). CONCLUSIONS: Viral enteropathogens, particularly norovirus, are important contributors to MAAGE, especially among children < 5 years of age. The present findings underline the importance of judicious antibiotics use for pediatric AGE and suggest that an effective norovirus vaccine could substantially reduce MAAGE.

Rotavirus Vaccine Is Effective Against Rotavirus Gastroenteritis Resulting in Outpatient Care: Results From the Medically Attended Acute Gastroenteritis (MAAGE) Study.

BACKGROUND: Rotavirus is a common cause of severe pediatric acute gastroenteritis. Two vaccines are licensed in the United States and have demonstrated high effectiveness against moderate to severe disease. However, fewer data are available on rotavirus vaccine effectiveness (VE) against milder disease. METHODS: We leveraged active surveillance data from Kaiser Permanente Northwest to calculate rotavirus VE against medically attended rotavirus illness among age-eligible children. We utilized a test-negative case-control design and applied 4 distinct case definitions based on reverse transcription-quantitative real-time PCR (qRT-PCR) assay and enzyme immunoassay (EIA) test results. VE was calculated as 100 × (1 - odds ratio), and models were adjusted for age group. RESULTS: The VE analysis population comprised 842 children, 799 (95%) of whom had mild disease requiring at most a clinic visit and 698 (83%) of whom were fully vaccinated against rotavirus. Age-adjusted VE was 70% (95% confidence interval [CI], 37-86%) against disease defined solely by qRT-PCR results, 72% (95% CI, 31-89%) against disease as defined by qRT-PCR with a quantification cycle (C q ) value <27, 73% (95% CI, 32-90%) against disease that was qRT-PCR positive but EIA negative, and 62% (95% CI, -20-88%) against disease defined solely by EIA. Results were similar when restricting to disease resulting in at most an ambulatory clinic or emergency department visit. CONCLUSIONS: These results support the effectiveness of rotavirus vaccination in protecting US children from mild to moderate and severe disease. Our findings are also useful to show the effectiveness of rotavirus vaccination against qRT-PCR-defined illness.

Incidence of SARS-CoV-2 Infection, Emergency Department Visits, and Hospitalizations Because of COVID-19 Among Persons Aged ≥12 Years, by COVID-19 Vaccination Status - Oregon and Washington, July 4-September 25, 2021.

Population-based rates of infection with SARS-CoV-2 (the virus that causes COVID-19) and related health care utilization help determine estimates of COVID-19 vaccine effectiveness and averted illnesses, especially since the SARS-CoV-2 B.1.617.2 (Delta) variant began circulating in June 2021. Among members aged ≥12 years of a large integrated health care delivery system in Oregon and Washington, incidence of laboratory-confirmed SARS-CoV-2 infection, emergency department (ED) visits, and hospitalizations were calculated by COVID-19 vaccination status, vaccine product, age, race, and ethnicity. Infection after full vaccination was defined as a positive SARS-CoV-2 molecular test result ≥14 days after completion of an authorized COVID-19 vaccination series.* During the July-September 2021 surveillance period, SARS-CoV-2 infection occurred among 4,146 of 137,616 unvaccinated persons (30.1 per 1,000 persons) and 3,009 of 344,848 fully vaccinated persons (8.7 per 1,000). Incidence was higher among unvaccinated persons than among vaccinated persons across all demographic strata. Unvaccinated persons with SARS-CoV-2 infection were more than twice as likely to receive ED care (18.5%) or to be hospitalized (9.0%) than were vaccinated persons with COVID-19 (8.1% and 3.9%, respectively). The crude mortality rate was also higher among unvaccinated patients (0.43 per 1,000) than in fully vaccinated patients (0.06 per 1,000). These data support CDC recommendations for COVID-19 vaccination, including additional and booster doses, to protect individual persons and communities against COVID-19, including illness and hospitalization caused by the Delta variant (1).

All-Cause Mortality and Progression Risks to Hepatic Decompensation and Hepatocellular Carcinoma in Patients Infected With Hepatitis C Virus.

BACKGROUND: A key question in care of patients with chronic hepatitis C virus (HCV) infection is beginning treatment immediately vs delaying treatment. Risks of mortality and disease progression in "real world" settings are important to assess the implications of delaying HCV treatment. METHODS: This was a cohort study of HCV patients identified from 4 integrated health systems in the United States who had liver biopsies during 2001-2012. The probabilities of death and progression to hepatocellular carcinoma, hepatic decompensation (hepatic encephalopathy, esophageal varices, ascites, or portal hypertension) or liver transplant were estimated over 1, 2, or 5 years by fibrosis stage (Metavir F0-F4) determined by biopsy at beginning of observation. RESULTS: Among 2799 HCV-monoinfected patients who had a qualifying liver biopsy, the mean age at the time of biopsy was 50.7 years. The majority were male (58.9%) and non-Hispanic white (66.9%). Over a mean observation of 5.0 years, 261 (9.3%) patients died and 34 (1.2%) received liver transplants. At 5 years after biopsy, the estimated risk of progression to hepatic decompensation or hepatocellular carcinoma was 37.2% in stage F4, 19.6% in F3, 4.7% in F2, and 2.3% in F0-F1 patients. Baseline biopsy stage F3 or F4 and platelet count below normal were the strongest predictors of progression to hepatic decompensation or hepatocellular carcinoma. CONCLUSIONS: The risks of death and progression to liver failure varied greatly by fibrosis stage. Clinicians and policy makers could use these progression risk data in prioritization and in determining the timing of treatment for patients in early stages of liver disease.

Health Care Utilization and Clinical Management of All-Cause and Norovirus-Associated Acute Gastroenteritis Within a US Integrated Health Care System.

Background: Norovirus-associated acute gastroenteritis (AGE) exacts a substantial disease burden, yet the health care utilization for and clinical management of norovirus-associated AGE are not well characterized. Methods: We describe the health care encounters and therapeutics used for patients with all-cause and norovirus-associated AGE in the Kaiser Permanente Northwest health system from 1 April 2014 through 30 September 2016. Medical encounters for patients with AGE were extracted from electronic health records, and encounters within 30 days of one another were grouped into single episodes. An age-stratified random sample of patients completed surveys and provided stool samples for norovirus testing. Results: In total, 40 348 individuals had 52 509 AGE episodes; 460 (14%) of 3310 participants in the substudy tested positive for norovirus. An overall 35% of all-cause AGE episodes and 29% of norovirus-associated AGE episodes had ≥2 encounters. While 80% of norovirus-associated AGE episodes had at least 1 encounter in the outpatient setting, all levels of the health care system were affected: 10%, 22%, 10%, and 2% of norovirus-associated AGE episodes had at least 1 encounter in virtual, urgent care, emergency department, and inpatient settings, respectively. Corresponding proportions of therapeutic use between norovirus-positive and norovirus-negative episodes were 13% and 10% for intravenous hydration (P = .07), 65% and 50% for oral rehydration (P < .001), 7% and 14% for empiric antibiotic therapy (P < .001), and 33% and 18% for antiemetics (P < .001). Conclusions: Increased health care utilization and therapeutics are likely needed for norovirus-associated AGE episodes during peak norovirus winter seasons, and these data illustrate that effective norovirus vaccines will likely result in less health care utilization.

Attitudes toward a future norovirus vaccine among members of an integrated healthcare delivery system in Portland, Oregon, 2016-2017.

With recent advances in U.S. clinical trials for norovirus vaccines, it is an opportune time to examine what is known about the public receptivity to this novel vaccine. From October 2016-September 2017, we surveyed Kaiser Permanente Northwest members in Portland, Oregon, to ask their level of agreement on a 5-point scale with statements about the need for and willingness to get a potential norovirus vaccine for themselves or their child and analyzed their responses according to age, occupational status, prior vaccine uptake, and history of prior norovirus diagnoses. The survey response rate was 13.5% (n = 3,894); 807 (21%) responded as legal guardians, on behalf of a child <18 y of age and 3,087 (79%) were adults aged 18+ y. The majority of respondents were in agreement about getting the norovirus vaccine, if available (60% of legal guardians, 52% of adults aged 18-64 y, and 55% of adults aged 65+ y). Prior vaccination for influenza and rotavirus (among children) was the only correlate significantly associated with more positive attitudes toward receiving norovirus vaccine. Pre-pandemic attitudes in our all-ages study population reveal generally positive attitudes toward willingness to get a norovirus vaccine, particularly among those who previously received influenza or rotavirus vaccines.

Burden of Medically Attended Diarrhea and Outpatient Clostridioides difficile Infection Among Persons in 2 Large Integrated Healthcare Settings, 2016-2021.

Background: Identification of Clostridioides difficile infection (CDI) in the community setting is increasing. We describe testing for CDI among patients with medically attended diarrhea (MAD) in the outpatient setting, and the incidence of outpatient CDI. Methods: This was a retrospective cohort study among members ≥18 years of age from Kaiser Permanente Southern California and Kaiser Permanente Northwest from 1 January 2016 through 31 December 2021. MAD was identified by outpatient diarrheal International Classification of Diseases, Tenth Revision diagnosis codes, and CDI through positive laboratory results. Outpatient CDI was defined by no hospitalization ≤7 days after specimen collection. Incidence rates (IRs) of outpatient CDI were stratified by select demographic and clinical variables. Outpatient CDI burden 12 months following index date was measured by CDI-associated healthcare visits, and CDI testing and treatment. Results: We identified 777 533 MAD episodes; 12.1% (93 964/777 533) were tested for CDI. Of those tested, 10.8% (10 110/93 964) were positive. Outpatient CDI IR was 51.0 (95% confidence interval [CI], 49.8-52.2) per 100 000 person-years, decreasing from 58.2 (95% CI, 55.7-60.7) in 2016 to 45.7 (95% CI, 43.7-47.8) in 2021. Approximately 44% (n = 4200) received an antibiotic 30 days prior to index date and 84.1% (n = 8006) CDIs were "community-associated" (no hospitalizations 12 weeks prior to index date). Of outpatient CDIs, 6.7% (n = 526) had a CDI-associated hospitalization ≤12 months. Conclusions: There was a high incidence of outpatient CDI despite infrequent CDI testing among patients with MAD. The majority of those with outpatient CDI had no recent antibiotic use and no recent hospitalization. Further studies are needed to understand the source and management of medically attended outpatient CDI.

Care trajectories for patients utilizing electronic visits for COVID-like symptoms in a large healthcare delivery system: May 2020-December 2021.

BACKGROUND: There is limited information about how on-line screening tools developed by integrated systems facilitated management of COVID-like illness patients. METHODS: Using the Kaiser Permanente Northwest (KPNW) Electronic Health Record, we identified adult plan members who accessed online COVID-19 screening e-visits and enumerated their subsequent medical encounters, tests for SARS-CoV-2, and test outcomes. RESULTS: Between May 2020 and December 2021, members completed 55,139 e-visits, with disproportionate representation among females (65% vs. 53% in the overall membership) and members aged <45 years (61% vs. 39%). Thirty percent of patients (16,953) were managed entirely through e-visits and 70% received subsequent in-person care. The percent of SARS-CoV-2 positive individuals was highest among the 1055 individuals triaged to inpatient care (17.9%), compared to 9.5% among those escalated to additional ambulatory care. CONCLUSIONS: The e-visit on-line screening tool helped KPNW assist thousands of patients with COVID-19 symptoms, avoid unnecessary in-person patient encounters, and preserved KPNW infection control and pandemic surge capacity.

Correlates of healthcare-seeking behavior for acute gastroenteritis-United States, October 1, 2016 -September 30, 2017.

BACKGROUND: In the United States, public health surveillance systems often underestimate the burden of acute gastroenteritis (AGE) because they only identify disease among those who interact with the healthcare system. OBJECTIVE: To identify factors associated with healthcare-seeking behavior among individuals experiencing community-acquired AGE. METHODS: From October 2016 -September 2017, we conducted a weekly, age-stratified, random sample of Kaiser Permanente Northwest members located in northwest Oregon and southwest Washington, United States. Individuals who completed the online survey and experienced AGE were included in the analysis. Univariate and multivariable logistic regressions were performed to identify predictors of healthcare-seeking behavior. RESULTS: Of the 3,894 survey respondents, 395 experienced an AGE episode and were eligible for analysis, of whom, 82 (21%) sought care for their AGE episode. In the final multivariable model, individuals with a concurrent fever (odds ratio [OR]: 4.76, 95% confidence interval [95% CI]: 2.48-9.13), increased diarrhea duration (≥6 days vs 1-4 days, OR: 4.22, 95% CI: 1.78-10.03), or increased vomiting duration (≥3 days vs 1 days, OR: 2.97, 95% CI: 1.22-7.26), were significantly more likely to seek healthcare. In the adjusted model, no sociodemographic or chronic disease variables were associated with healthcare-seeking behavior. CONCLUSION: These findings suggest that individuals with a short duration of AGE and those without concurrent fever are underrepresented in healthcare facility-based surveillance systems.

Household Transmission of Viral Acute Gastroenteritis Among Participants Within an Integrated Health Care Delivery System, 2014-2016.

Background: While enteric viruses are highly transmissible, household factors associated with transmission are less well documented. We identified individual- and household-level factors associated with viral acute gastroenteritis (AGE) transmission in a large health care network in the United States. Methods: Patients presenting with AGE were enrolled from April 2014 to September 2016. Patients and symptomatic household members were interviewed, and stool specimens were collected and tested for viral pathogens. Within a household, primary cases were those with the earliest symptom onset and a positive viral test result; secondary cases were household contacts (HHCs) with symptom onset 1-7 days from the primary case onset. Transmission households had at least 1 secondary case. Results: Our analysis included 570 primary cases with 1479 HHCs. The overall secondary attack rate was 23%. HHCs were likely to become secondary cases (n = 338) if they were <5 years old (adjusted odds ratio [aOR], 1.8; 95% CI, 1.2-2.6). Secondary transmission was likely to occur if the primary case was aged <5 years (aOR, 2.2; 95% CI, 1.4-3.6) or 5 to 17 years (aOR, 3.3; 95% CI, 1.9-5.7), was norovirus positive (aOR, 2.7; 95% CI, 1.9-3.7), had a diapered contact (aOR: 2.2, 95% CI: 1.6-3.2), or reported symptoms for >4 days (aOR, 1.5; 95% CI, 1.1-2.1). Households with ≥3 members (aOR, 2.1; 95% CI, 1.1-4.5) were more likely to experience transmission. Discussion: Risk of AGE transmission within households increased if the primary case was younger, was norovirus positive, had a longer symptom duration, or had a diapered contact. Targeted prevention messaging around appropriate cleaning, disinfection, and isolation of persons with AGE should be encouraged.

Rotavirus Vaccine Impact Within an Integrated Healthcare Delivery System in the United States.

We assessed rotavirus vaccine impact using data on acute gastroenteritis (AGE) encounters within an integrated healthcare delivery system during 2000-2018. Following rotavirus vaccine introduction, all-cause AGE rates among children <5 years declined by 36% (95% confidence interval [CI]: 32%-40%) for outpatient and 54% (95% CI: 46%-60%) for inpatient encounters.

A model for rapid, active surveillance for medically-attended acute gastroenteritis within an integrated health care delivery system.

BACKGROUND: This study presents a novel methodology for estimating all-age, population-based incidence rates of norovirus and other pathogens that contribute to acute gastroenteritis in the United States using an integrated healthcare delivery system as a surveillance platform. METHODS: All cases of medically attended acute gastroenteritis within the delivery system were identified from April 1, 2014 through September 30, 2016. A sample of these eligible patients were selected to participate in two phone-based surveys and to self-collect a stool sample for laboratory testing. To ascertain household transmission patterns, information on household members with acute gastroenteritis was gathered from participants, and symptomatic household members were contacted to participate in a survey and provide stool sample as well. RESULTS: 54% of individuals who met enrollment criteria agreed to participate, and 76% of those individuals returned a stool sample. Among household members, 85% of eligible individuals agreed to participate, and 68% of those returned a stool sample. Participant demographics were similar to those of the eligible population, although minority racial/ethnic groups were somewhat underrepresented in the final sample. CONCLUSIONS: This study demonstrates the feasibility of conducting acute infectious disease research within an integrated health care delivery system. The surveillance, sampling, recruitment, and data collection methods described here are broadly applicable to conduct baseline and epidemiological assessments, as well as for other research requiring representative samples of stool specimens.

The role of the coordinating center in the obesity prevention at the worksite consortium.

This paper describes the role of the Coordinating Center for a seven-project consortium funded through a common request for applications. The seven studies are focusing on prevention and treatment of obesity at worksites. These projects are being conducted at different types of work sites that have diverse employee populations. The Center's functions include identifying opportunities for collaboration, encouraging communication among the project investigators, facilitating the adoption of common measures, combining data from two or more projects to achieve greater statistical power, and pooling data on measures such as physical activity, work productivity, health care use, and return on investment. To these ends, the Coordinating Center helped to develop a committee structure within the consortium, established a communications and data transmission web site, and arranged conference calls, committee meetings, and paper writing groups. The development and implementation of these functions are described in this paper.