Streptococcus pneumoniae nasal carriage patterns with and without common respiratory virus detections in households in Seattle, WA, USA before and during the COVID-19 pandemic

Background

Respiratory viruses might influence Streptococcus pneumoniae nasal carriage and subsequent disease risk. We estimated the association between common respiratory viruses and semiquantitative S. pneumoniae nasal carriage density in a household setting before and during the COVID-19 pandemic.

Methods

From November 2019-June 2021, we enrolled participants in a remote household surveillance study of respiratory pathogens. Participants submitted weekly reports of acute respiratory illness (ARI) symptoms. Mid-turbinate or anterior nasal swabs were self-collected at enrollment, when ARI occurred, and, in the second year of the study only, from household contacts after SARS-CoV-2 was detected in a household member. Specimens were tested using multiplex reverse-transcription PCR for respiratory pathogens, including S. pneumoniae, rhinovirus, adenovirus, common human coronavirus, influenza A/B virus, respiratory syncytial virus (RSV) A/B, human metapneumovirus, enterovirus, and human parainfluenza virus. We estimated differences in semiquantitative S. pneumoniae nasal carriage density, estimated by the inverse of S. pneumoniae relative cycle threshold (Crt) values, with and without viral detection for any virus and for specific respiratory viruses using linear generalized estimating equations of S. pneumoniae Crt values on virus detection adjusted for age and swab type and accounting for clustering of swabs within households.

Results

We collected 346 swabs from 239 individuals in 151 households that tested positive for S. pneumoniae (n = 157 with and 189 without ≥1 viruses co-detected). Difficulty breathing, cough, and runny nose were more commonly reported among individuals with specimens with viral co-detection compared to without (15%, 80% and 93% vs. 8%, 57%, and 51%, respectively) and ear pain and headache were less commonly reported (3% and 26% vs. 16% and 41%, respectively). For specific viruses among all ages, semiquantitative S. pneumoniae nasal carriage density was greater with viral co-detection for enterovirus, RSV A/B, adenovirus, rhinovirus, and common human coronavirus (P < 0.01 for each). When stratified by age, semiquantitative S. pneumoniae nasal carriage density was significantly greater with viral co-detection among children aged <5 (P = 0.002) and 5-17 years (P = 0.005), but not among adults aged 18-64 years (P = 0.29).

Conclusion

Detection of common respiratory viruses was associated with greater concurrent S. pneumoniae semiquantitative nasal carriage density in a household setting among children, but not adults.

School-Based Interventions to Increase Student COVID-19 Vaccination Coverage in Public School Populations with Low Coverage - Seattle, Washington, December 2021-June 2022

COVID-19 can lead to severe outcomes in children (1). Vaccination decreases risk for COVID-19 illness, severe disease, and death (2). On December 13, 2020, CDC recommended COVID-19 vaccination for persons aged ≥16 years, with expansion on May 12, 2021, to children and adolescents (children) aged 12-15 years, and on November 2, 2021, to children aged 5-11 years (3). As of March 8, 2023, COVID-19 vaccination coverage among school-aged children remained low nationwide, with 61.7% of children aged 12-17 years and approximately one third (32.7%) of those aged 5-11 years having completed the primary series (3). Intention to receive COVID-19 vaccine and vaccination coverage vary by demographic characteristics, including race and ethnicity and socioeconomic status (4-6). Seattle Public Schools (SPS) implemented a program to increase COVID-19 vaccination coverage during the 2021-22 school year, focusing on children aged 5-11 years during November 2021-June 2022, with an added focus on populations with low vaccine coverage during January 2022-June 2022.^† The program included strategic messaging, school-located vaccination clinics, and school-led community engagement. Vaccination data from the Washington State Immunization Information System (WAIIS) were analyzed to examine disparities in COVID-19 vaccination by demographic and school characteristics and trends over time. In December 2021, 56.5% of all SPS students, 33.7% of children aged 5-11 years, and 81.3% of children aged 12-18 years had completed a COVID-19 primary vaccination series. By June 2022, overall series completion had increased to 80.3% and was 74.0% and 86.6% among children aged 5-11 years and 12-18 years, respectively. School-led vaccination programs can leverage community partnerships and relationships with families to improve COVID-19 vaccine access and coverage.

1904. Health Behavioral Trends and Absenteeism Associated with Acute Respiratory Illness Before and During the SARS-CoV-2 Pandemic in a Community Household Cohort, King County, Washington

Background

Non-pharmaceutical interventions (NPIs), such as masking and social distancing, can reduce SARS-CoV-2 transmission. Longitudinal behavioral data in individuals with acute respiratory illness (ARI) during the COVID-19 pandemic are limited. We describe changes in adherence to NPIs and the impact of ARIs on work or school in families before and during the COVID-19 pandemic.

Methods

From November 2019 to June 2021, households with school-aged children in King County, WA, were remotely monitored on a weekly basis for symptoms of respiratory illness. Participants with ARI (cough or ≥2 qualifying symptoms) were asked about illness-related behavior changes (e.g. masking, isolation, hand hygiene, surface cleaning, public transit use) and impacts on school/work 7 days after initial symptom report. Using generalized estimating equations for household clusters, we compared the frequency of behavior changes and school/work impact during 3 time periods: the pre-/early COVID-19 pandemic period (11/14/19-3/22/20), pre-vaccine period (3/23/20-12/10/20), and post-COVID-19 vaccine period (12/11/20-6/19/21).

Results

Of 1861 participants in 470 households, 695 (37%, from 70% of households) reported 1157 ARIs. Over the 3 time periods, the percent of ill participants who reported staying home (34 vs 34 vs 54%, respectively, P&lt; .001), avoiding contact with others (25 vs 28 vs 45%, P&lt; .001), and masking (3 vs 23 vs 38%, P&lt; .001) increased (Fig 1A). Other illness-related behaviors, including washing hands and disinfecting surfaces, were unchanged over time. The percent of ill participants who worked from home (7 vs 9 vs 3%, P= .02) and missed work due to ARI (13 vs 8 vs 8%, P= .03) decreased over time (Fig 1B). Figure 1A.Participant reported illness-related health behaviors in the past week — Seattle, WA, 2019–2021.Figure 1B.Participant reported illness-related school or work impact in the past week due to illness — Seattle, WA, 2019–2021

Time periods were defined as: Period 1: 11/14/19 – 3/22/20 (pre-/early COVID-19 pandemic), Period 2: 3/23/20 – 12/10/20 (post-Washington State Stay at Home order), and Period 3: 12/11/20 – 6/19/21 (United States Food and Drug Administration Emergency Use Authorization for the Pfizer-BioNTech COVID-19 vaccine for those 16 years and older). Illness was defined per Acute Respiratory Illness (ARI) case definition: cough or two qualifying symptoms (fever, sore throat, runny nose, muscle or body aches, headache, difficulty breathing, fatigue, nausea or vomiting; for participants &lt; 18 years of age, ear pain or drainage, rash, and diarrhea were also qualifying symptoms).

Conclusion

As the COVID-19 pandemic progressed, households with school-aged children engaged in isolation, social distancing, and masking more frequently in response to ARI. The impact of ARIs on work decreased during the pandemic.

Disclosures

Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Helen Y. Chu, MD, MPH, Cepheid: Reagents|Ellume: Advisor/Consultant|Gates Ventures: Grant/Research Support|Merck: Advisor/Consultant|Pfizer: Advisor/Consultant.

2202. Influenza Surveillance of Families in an Observational Household Study 2019-2021

Background

Families with children may be at higher risk for influenza infection. Community transmission can suffer from underreporting as testing is often not performed. We studied the epidemiology of influenza in households with school-aged children using home-based sample collection.

Methods

We conducted a remote household study surveilling respiratory viruses from November 2019-June 2021, in King County, Washington (WA), USA. Households with school-aged children were enrolled, mailed home specimen collection kits, and asked to self-assess for weekly acute respiratory illness (ARI) using remote survey platforms. Participants with ARI symptoms were prompted to complete serial illness surveys and self-collect/parent collect mid-turbinate nasal swabs. Samples were sent to a University of Washington study laboratory for RT-PCR influenza testing. Influenza rates were compared to WA Department of Health (DOH) reporting.

Results

A total of 1861 ARI events were reported among 992 adults and 869 children in 470 households; 75 influenza cases were detected (36 influenza A and 39 influenza B). The study participant median age was 32 years (0-84), 10 years (1-49) for influenza A, and 11 years (3-49) for influenza B cases. Overall 13% of households had an influenza case, of which 13 (22%) reported >1 case. A total of 81% of participants reported receipt of one dose of the 2019-2020 influenza vaccine, including 91% of influenza A and 90% of influenza B cases, and 84% received the 2020-2021 influenza vaccine. Like WA DOH, we observed a wave of influenza B cases followed by influenza A in 2019-2020. During influenza season 2020-2021, WA DOH reported 9 positive influenza tests and none observed in our study. Commonly, influenza case-patients reported were fever, cough, rhinorrhea, and fatigue. GI symptoms were more common in children than adults. Of the cases, 92% of influenza A and 78% of influenza B occurred in children. Figure 1.

Community-Engaged Approach to the Development and Implementation of a Student-Centered Return to Learn Care Plan After Concussion

BACKGROUND

Current return to learn (RTL) after concussion guidelines lack specificity for individualized student care, limiting potential for adoption and implementation. We used a community-engaged research framework to develop and evaluate the implementation of a student-centered care plan that assists school personnel in facilitating RTL.

METHODS

We used best-practice RTL guidelines and input from administrators and medical experts to iteratively develop a flexible student-centered care plan. Thirteen schools participated. Coding completion of care plans indicated feasibility and fidelity; interviews with RTL coordinators indicated acceptability.

RESULTS

The care plan includes educational materials, symptom checklists, and guidelines for classroom adjustments linked to student symptoms. Care plans were initiated for 24 (70.6%) of 34 students with concussions, indicating feasibility. Fidelity was high, with the following subsections completed: Action Checklist (90%), Symptom Evaluation (91%), Temporary Adjustment Recommendations (95%). Qualitative analysis of interviews suggested care plans were acceptable and facilitate consistent communication, prioritization of individual needs of students, and increased ability to delegate tasks to other school staff.

CONCLUSIONS

Implementation of a student-centered, individually tailored care plan for RTL is feasible and acceptable in public high schools. Future research should examine how to expediently initiate student-centered concussion care plans after diagnosis to optimize recovery.

Comparison of bovine in vivo bioavailability of two sulfamethazine oral boluses exhibiting different in vitro dissolution profiles

The bolus (or oblet) is a dosage form that can be used for the oral administration of pharmaceutical compounds to ruminating species. Unlike traditional tablets, oral boluses may contain quantities of drug on the order of grams rather than milligrams. Due to its size, it is only recently that USP-like in vitro dissolution methods have been developed for this dosage form. However, whether or not these dissolution tests can predict product in vivo performance has yet to be determined. The importance of this issue is apparent when the U.S. Food and Drug Administration Center for Veterinary Medicine is faced with the decision of whether to require additional in vivo bioequivalence study data to support the approval of changes in product chemistry or manufacturing method. The current study was undertaken to determine whether an in vivo/in vitro correlation can be established for bovine sulfamethazine oral boluses and to acquire insight into the magnitude of changes in in vitro product performance that can occur before corresponding changes are seen in in vivo blood level profiles. Based upon the results of this investigation, it is concluded that marked changes in in vitro sulfamethazine bolus performance can be tolerated before resulting in altered in vivo blood level profiles. However, the data also suggest that rumenal absorption may occur for some compounds. Therefore the degree to which variation in product in vitro dissolution profiles can be tolerated may be compound specific.

Setting rates for Medicaid managed behavioral health care: lessons learned

This paper reviews Tennessee's experience setting, monitoring, and updating capitation rates for Medicaid managed behavioral health care, and draws lessons from those experiences for other states. Our review of assumptions about four components of Tennessee's rate-setting process--data, benefit design, savings expectations, and processes for monitoring and updating rates--suggests that the initial rate established by Tennessee was inadequate, and its inadequacy resulted primarily from the way available information was used to set the rate, rather than from the method of rate setting selected. Tennessee's experiences illustrate how difficult rate setting is and illuminate several key lessons about the rate-setting process.

Evolution of Medicaid managed care systems and eligibility expansions

The States of Tennessee, Hawaii, Rhode Island, Oklahoma, and Maryland initiated section 1115 demonstration projects to reform their State Medicaid programs, featuring large expansions of Medicaid managed care. The projects were controversial and chaotic in the beginning but have matured with time. Survey data indicate that Tennessee's expansion reduced uninsurance rates among low-income persons. States must periodically assess the adequacy of capitation rates to ensure that enough plans participate. States and plans gradually developed their quality assurance systems but still need improvement.

Medicaid managed care and the marketplace

In 1994 and 1995, Tennessee, Hawaii, Rhode Island, and Oklahoma began massive expansions of Medicaid managed care, growing from three health plans covering a few enrollees to 27 plans covering the great majority a year later. Some firms aggressively pursued expansion, while others had very limited business objectives. Although established insurers often dominated the Medicaid markets, newly developed firms, some provider-sponsored, were also important. Despite the relatively low Medicaid capitation rates in the 1996-97 period, Medicaid plans in three states had an average 1% net profit margin.

Population screening for glucose intolerant subjects using decision tree analyses

The purpose of this study was to develop a method of screening for impaired glucose tolerance and previously undiagnosed NIDDM that could be used preliminary to the administration of an oral glucose tolerance test (OGTT) for final classification of glucose tolerance status. The purpose of a preliminary screening of this type would be to reduce the number of OGTT's needed to identify cases of IGT and NIDDM in the population. We used NIDDM risk indicators and decision tree analysis methods (CART software) to identify subgroups of the population at increased risk. We examined a population of Hispanic (n = 583) and non-Hispanic white (n = 768) subjects without a prior history of diabetes. Subjects were classified as normal, IGT or NIDDM (WHO criteria) based on results from a 75 g oral glucose tolerance test (OGTT). Sensitivity (SEN) and specificity (SPE) of the CART models were calculated using the OGTT as the 'gold standard.' Two approaches to screening were simulated. In the simultaneous approach all risk variables were entered into CART models at once. In the serial approach, risk variables were grouped according to degree of effort required for data collection, and were entered into CART models in stages. Fasting glucose, age and body mass index (BMI) were selected as risk variables by CART when simulating the simultaneous approach (SEN = 91%, SPE = 55%). In the serial approach, CART used age and BMI to eliminate 35% of the population from further screening, and then used fasting glucose, glycohemoglobin, age and BMI to classify the remaining higher risk subjects (SEN = 85%, SPE = 64%). These models suggest that screening for IGT and previously undiagnosed NIDDM can be based on measurement of relatively simple indicators, and yet maintain a level of both sensitivity and specificity acceptable for this type of preliminary screening.

Associations between dietary factors and serum lipids by apolipoprotein E polymorphism

A geographically based observational study of 852 nondiabetic Hispanic and non-Hispanic white persons in southern Colorado aged 20-74 y was conducted to determine whether diet-lipid associations were modified by the apolipoprotein E (apoE, protein; APOE, gene) polymorphism. Subjects were seen for up to three visits from 1984 to 1992. A 24-h diet recall was collected and fasting serum lipid concentrations were measured at all visits. In longitudinal-regression analyses, dietary factors were significantly associated with serum lipid concentrations in the directions expected based on the large amount of literature on this topic. The positive relation between dietary cholesterol and serum total and low-density-lipoprotein cholesterol was strongest in Hispanic subjects with the APOE*2 allele (E2/ 2,3/2 genotypes) and non-Hispanic white subjects with the APOE*3 allele (E3/3 genotype), and there was no association in subjects with the APOE*4 allele (E4/3, 4/4 genotypes) in either ethnic group. No other statistically significant differences in the relations between dietary factors and serum lipid concentrations by APOE polymorphism were identified. These findings suggest that the APOE polymorphism plays only a minor role in modifying the association between dietary factors and serum lipids.

Effect of diagnostic criteria on the prevalence of peripheral arterial disease. The San Luis Valley Diabetes Study

BACKGROUND

The ankle/brachial systolic blood pressure index (ABI), a noninvasive measure of peripheral arterial disease (PAD), is widely used in epidemiological studies. However, the normal ranges of the ABI in healthy populations and ABI criteria for the diagnosis of PAD in large population studies have not been critically evaluated.

METHODS AND RESULTS

The San Luis Valley Diabetes Study (SLVDS) was designed to evaluate the prevalence and complications of non-insulin-dependent diabetes mellitus (NIDDM) in a biethnic population. The present study was conducted as part of the SLVDS to assess the prevalence of vascular disease in 1280 nondiabetic control subjects and 430 patients with NIDDM. The ABI criteria for PAD were developed in 403 healthy individuals with a low risk for cardiovascular disease. In these low-risk subjects, the average resting ABI value was 0.07 lower in women than in men. In both sexes, the dorsalis pedis ABI was 0.04 lower than in the posterior tibial artery, and the left leg ABI was 0.02 lower than the right leg ABI (all differences, P < .05). In the low-risk subjects, ABI values were lower after exercise than at rest and had similar differences by sex and leg as observed at rest. Using specific abnormal cutoff points for the ABI, we evaluated three criteria for PAD in the overall population: two abnormal vessels in the same leg at rest (both dorsalis pedis and posterior tibial arteries), one abnormal vessel per leg at rest, and an ABI abnormality only after exercise. Subjects classified with PAD by the two-vessel criterion had a higher frequency of claudication and the physical finding of an absent pulse compared with subjects without PAD or patients with PAD defined by the one-vessel or exercise criterion. Use of the two-vessel criterion identified an increased risk of PAD with increasing age, NIDDM, smoking, hypertension, and elevated cholesterol levels. In contrast, the one-vessel PAD criterion was associated only with increasing age and smoking, and exercise-diagnosed PAD was not associated with any cardiovascular risk factor except for male sex.

CONCLUSIONS

In low-risk subjects, the normal distribution and lower abnormal cutoff point values of the ABI differed by type of test, sex, ankle vessel, and leg. When these specific abnormal cutoff points were applied to the SLVDS population, the two-vessel abnormal criterion described patients with typical clinical characteristics of PAD and the expected associations of PAD with cardiovascular risk factors. These clinical characteristics and cardiovascular risk factor associations were less evident with PAD diagnosed by the one-vessel or exercise criterion. Therefore, an abnormal dorsalis pedis and posterior tibial ABI in the same leg at rest should be used for the diagnosis of PAD in epidemiological studies.

High fasting insulin levels associated with lower rates of weight gain in persons with normal glucose tolerance: the San Luis Valley Diabetes Study

OBJECTIVE

to investigate whether increased insulin resistance is associated with a reduced risk of weight gain among Hispanic and non-Hispanic white persons in Colorado.

DESIGN

measurements were taken at baseline and after an average of 4.3 years.

SUBJECTS

789 normal glucose tolerant subjects 20 to 74 years of age were studied.

MEASUREMENTS

fasting insulin levels were used as an indirect marker of insulin resistance.

RESULTS

the average baseline body mass index (BMI) was 26.1 (+/- 3.6 s.d.) in men and 25.2 (+/- 4.4 s.d.) in women. The average weight change at follow-up was 0.8 kg (+/- 4.3 s.d.) in men and 1.3 kg (+/- 5.0) in women. A doubling in initial fasting insulin was associated with a reduced risk of gaining 5 kg (n = 134) and 10 kg (n = 24) of weight in logistic regression models (OR5kg = 0.76, 95% CI: 0.59, 0.99 and OR10kg = 0.61, 95% CI: 0.36, 1.02). Similarly, a doubling of initial fasting insulin was associated (P = 0.006) on average with a 6.3 kg less weight gain in linear regression models, independently of initial body weight, age, sex, ethnicity and BMI. The relation was consistently observed in men and women and in both ethnic groups.

CONCLUSION

higher initial fasting insulin decreases the risk of subsequent weight gain in both Hispanic and non-Hispanic white normal glucose tolerant individuals similar to Pima Indians. This appears to be a common biologic characteristic in moderate to low as well as high risk populations for NIDDM.

ApoA-IV polymorphism associated with myocardial infarction in obese NIDDM patients. The San Luis Valley Diabetes Study

Non-insulin-dependent diabetes mellitus (NIDDM) confers myocardial infarction (MI) risk unexplained by known factors. In 356 NIDDM patients and 1,087 people with normal glucose tolerance, we investigated the association between MI risk and polymorphism at codon 360 in the apolipoprotein A-IV (apoA-IV) gene. During 1984-1992, MI was diagnosed in 84 diabetic and in 106 nondiabetic people. The risk of MI did not differ by apoA-IV phenotype in nondiabetic people; however, in NIDDM patients, those with the apoA-IV 1-2 phenotype had 2.8 (95% confidence interval: 1.4-5.6) higher MI risk than those with the 1-1 phenotype, adjusting for age, gender, ethnicity, hypertension, smoking, body mass index, fat centrality, and low-density lipoprotein and high-density lipoprotein cholesterol. The risk of MI was particularly high in obese NIDDM patients with the apoA-IV 1-2 phenotype: 5.1 (2.4-11.2) times that in obese apoA-IV 1-1 NIDDM patients and 7.7 (3.6-16.7) times that in lean nondiabetic people. The effect of apoA-IV 1-2 did not appear to be a part of the insulin-resistance syndrome nor was it dependent on diabetes duration or control. One half of the excess MI risk in the diabetic population studied was explained by the apoA-IV 1-2 phenotype. These results indicate that approximately 17% of NIDDM patients have a high MI risk apoA-IV phenotype that is particularly deleterious in obese patients.

Dietary fat predicts conversion from impaired glucose tolerance to NIDDM. The San Luis Valley Diabetes Study

OBJECTIVE

To determine if dietary fat intake measured at a baseline exam in subjects with impaired glucose tolerance (IGT) predicted the subsequent development of non-insulin-dependent diabetes mellitus (NIDDM).

RESEARCH DESIGN AND METHODS

Based on an oral glucose tolerance test (OGTT) (World Health Organization criteria), we identified 134 eligible subjects with IGT from a geographically based sample of subjects with no prior history of diabetes. One to three years after the baseline exam, 123 subjects (92%) had a repeat OGTT. Diet was assessed by a 24-h diet recall reported before the baseline OGTT.

RESULTS

The mean percentage of energy eaten as fat was 43.4% in 20 people subsequently developing NIDDM compared with 40.6% in 43 people remaining IGT and 38.9% in 60 subjects who subsequently reverted to normal glucose tolerance. In comparing the 20 subjects who developed NIDDM with the 103 who remained IGT or normal, an increase in fat intake of 40 g/day was associated with an increase in risk of NIDDM of 3.4-fold (95% confidence interval [CI] 0.8-13.6) adjusted for energy intake, age, sex, ethnicity, and obesity. The odds ratio increased to sixfold (95% CI 1.2-29.8) after adjustment for fasting glucose, insulin, and 1-h insulin.

CONCLUSIONS

Fat consumption significantly predicts NIDDM risk in subjects with IGT after controlling for obesity and markers of glucose metabolism.

Transfusion-acquired hepatitis A in a premature infant with secondary nosocomial spread in an intensive care nursery

An outbreak of hepatitis A involving 15 nurses, two premature infants, and the mother of one infant occurred in an intensive care nursery. The infants became infected after receiving blood transfusions from a donor who shortly thereafter experienced symptoms compatible with hepatitis A and was later found to have serologic evidence of acute hepatitis A. Hepatitis was not suspected clinically in the infants but was documented serologically. One of the infants had an ileostomy with liquid intestinal drainage. Her mother and most, if not all, of the nurses acquired hepatitis from this infant. All 15 nurses had contact with this infant, whereas only four nurses had contact with the second infant. The amount of contact nurses had with this infant clearly was related to their risk of infection. Nurses not actually assigned to this infant but who reported some contact had a significantly lower attack rate than those assigned to the infant. Among assigned nurses, those assigned to more than one shift had 4.7 times the risk of acquiring hepatitis than those assigned to one shift only. No specific nursing techniques or personal habits were documented as being significant risk factors in the infected group of nurses.

Prediction of serum gentamicin concentrations in patients undergoing hemodialysis

The predictability of a one-compartment pharmacokinetic model for estimating serum gentamicin concentrations in patients undergoing hemodialysis was studied. Nine hemodialysis patients with gram-negative bacillary infections requiring aminoglycoside therapy and with creatinine clearances of less than 1 ml/min were studied. A series of blood samples was assayed by radioimmunoassay to determine serum concentrations after an initial 1.5- to 2.0-mg/kg i.v. dose and throughout the dialysis period. These data were used to predict post-dialysis serum concentrations and post-dialysis doses needed to achieve therapeutic concentrations. The mean apparent volume of distribution for gentamicin was 0.26 +/- 0.06 liter/kg. The mean gentamicin half-life was 31.5 hours before dialysis and 7.6 hours during dialysis. No significant differences were found between predicted and measured peak gentamicin serum concentrations after dialysis; nor were there significant differences for peak serum concentrations obtained with a post-dialysis gentamicin dose (p less than 0.001). Neither the peaks predicted based on the individual patient's pharmacokinetic values nor those based on the average of the patients' pharmcokinetic values were statistically different from measured. The kinetic model developed can be used to determine gentamicin dosing for hemodialysis patients and to determine an average elimination rate constant for a given dialysis apparatus.