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Biomedical subjects

Kristin L Nichol

Publications and source records attributed to Kristin L Nichol.

15 recordsLinked to original sources
PubMed2004

Development and validation of a clinical prediction rule for hospitalization due to pneumonia or influenza or death during influenza epidemics among community-dwelling elderly persons.

BACKGROUND: Uncertainties among health care providers and patients about the risk of serious influenza-associated complications and the potential benefits of vaccination may contribute to unsatisfactorily low influenza vaccination rates. To quantify the risk of serious outcomes (hospitalization due to pneumonia or influenza or death due to any cause) during influenza seasons, we developed a clinical prediction rule for the probability of hospitalization due to pneumonia or influenza or death among elderly persons. METHODS: We developed the clinical prediction rule using data from linked administrative databases in a cohort of 16,280 noninstitutionalized and unvaccinated elderly persons. Validation of the rule was conducted in 5 unvaccinated and 6 vaccinated cohorts, each consisting of >11,000 elderly members of 3 managed care organizations. Logistic regression was used to produce a prognostic score on the basis of the following predictors: age; sex; presence of pulmonary, cardiac, and renal disease; dementia or stroke and cancer; number of outpatient visits; and hospitalization due to pneumonia or influenza during the previous year. RESULTS: Reliability of the regression model was good (P=.65, by goodness-of-fit test), and it discriminated well between those who did and those who did not experience an outcome (area under the receiver-operating curve, 0.83; 95% confidence interval, 0.81-0.85). Validation revealed moderately lower but acceptable discriminating values (0.72-0.81). In the derivation cohort, the prognostic accuracy of the rule was high when a cutoff score for the upper 50th percentile was used: > or =10 of 1000 subjects with a score in the upper 50th percentile were predicted to have an outcome, and 89% of all outcomes were observed in this high-risk group, whereas <10 of 1000 subjects with a score in the lower 50th percentile were predicted to have an outcome, and only 11% of outcomes occurred in this group. Among unvaccinated subjects in the single-derivation cohort and the 11 validation cohorts combined, the outcome event rates were 35 events/1000 subjects in the higher-risk group and 6 events/1000 subjects in the lower-risk group. With vaccination, these event rates dropped by 15 events/1000 subjects and 2 events/1000 subjects, respectively. CONCLUSIONS: This prediction rule may be a useful tool to complement other age-based strategies, to further encourage vaccination, especially among those at the highest risk of serious complications due to influenza.

Aged↗
PubMed2004

Adherence of mass vaccinators to timing guidelines for influenza vaccination.

BACKGROUND: With recent delays in influenza vaccine availability, practitioners have been encouraged to time vaccination activities to promote vaccination of high-priority groups first. This cross-sectional survey of persons vaccinated in nontraditional settings (NTS) by mass vaccinators was conducted to assess how effectively the mass vaccinators were able to implement these vaccination-timing guidelines. METHODS: In Minnesota, the Minnesota Visiting Nurse Agency (MVNA) is a major mass vaccinator in NTS. For the 2001-2002 vaccination season, MVNA developed several strategies designed to facilitate adherence to vaccination timing guidelines adopted by the Minnesota Department of Health. All persons vaccinated in the MVNA NTS clinics from October 2001 through December 2001 were surveyed in order to evaluate whether they were in a high-priority group and whether the timing of their vaccinations coincided with the timing promoted in the guidelines. RESULTS: A total of 46,174 of the 145,947 people vaccinated by the MVNA were vaccinated between October 14 and October 28, 2001, the time period designated for vaccination of high-priority groups. Of these, 41,143 (89%) responded to the priority group question and 27,211 (66%) indicated that they were in one of the targeted groups, including more than 19,000 Medicare recipients. At sites targeting senior citizens, more than 92% of initial vaccine recipients were in a targeted group. Overall, 48.4% of persons vaccinated at any time during the vaccination season were in a high-priority group. CONCLUSIONS: Mass vaccinators can successfully implement influenza vaccination timing guidelines in NTS.

Cross-Sectional Studies↗
PubMed2004

Influence of clinical case definitions with differing levels of sensitivity and specificity on estimates of the relative and absolute health benefits of influenza vaccination among healthy working adults and implications for economic analyses.

Clinical illness case definitions for influenza and methods used to define influenza seasons can vary substantially from study to study. These differences often result in differing levels of sensitivity, specificity and positive predictive value for the case definitions used. We explored the implications of different case definitions and outcome periods on estimates of influenza vaccine effectiveness and cost benefit by conducting additional analyses of data collected from a randomized, double blind, placebo controlled trial of the trivalent, intranasal, live attenuated influenza virus vaccine in healthy working adults. Febrile upper respiratory tract illnesses occurring during the peak influenza period was identified as the most specific clinical case definition expected to have the highest positive predictive value for true influenza whereas events occurring on a day with any symptom occurring during the entire outcome period was identified as the most sensitive clinical case definition with the lowest positive predictive value for influenza. As expected, the former provided the highest estimates of vaccine effectiveness (28.4% reduction in work loss days, 24.6% reduction in days with impaired productivity and 40.9% reduction in days with health care provider visits) but the lowest estimates of absolute reductions in events (42.4 work loss days prevented per 1000, 79.0 impaired productivity days per 1000, and 16.5 days with health care provider visits per 1000). On the other hand, events on days with any symptom during the entire outcome period provided the lowest estimates of vaccine effectiveness (18% reduction in work loss days, 18% reduction in days with impaired productivity, and 13% reduction in days with health care provider visits) but the highest estimates of absolute reductions in events (186.4 work loss days per 1000, 271.5 impaired productivity days per 1000, and 44.8 days with health care provider visits per 1000). When applied to a cost benefit analysis, the more specific case definition provided a break even cost for vaccination of US$ 6.58 whereas the more sensitive case definition provided a break even cost for vaccination of US$ 43.07. Clearly the latter combination is most appropriate when trying to assess the total population level impact of a vaccine preventable disease and the potential cost effectiveness of vaccination whereas the former may be most appropriate for assessing whether the vaccine actually works. The definitions of clinical influenza illness and outcome periods should be selected to match the study question.

Adult↗
PubMed2004

The Veterans Short Form 36 questionnaire is predictive of mortality and health-care utilization in a population of veterans with a self-reported diagnosis of asthma or COPD.

STUDY OBJECTIVE: Measures of health-related quality of life (HRQL) correlate with disease stage in persons with COPD. However, as their predictive capacity for mortality or medical utilization is less well defined, we sought to examine the relationship of a general measure of HRQL and outcomes in persons with obstructive lung disease. DESIGN: Prospective cohort study. SETTING: Upper Midwest Veterans Integrated Service Network (VISN)-13. PARTICIPANTS: All veterans in VISN-13 (n = 70,017) were surveyed with the Veterans Short Form 36 (SF-36V). Persons with reported asthma or COPD who completed the SF-36V formed the study cohort (n = 8,354). MEASUREMENTS AND RESULTS: For purposes of analysis, individuals were divided into quartiles of HRQL according to their physical component summary (PCS) and mental component summary (MCS), values derived from the SF-36V. Outcomes of mortality, hospitalization, and outpatient visits were recorded for 12 months after the survey. Outpatient utilization was dichotomized into high vs low use, with high use being defined as the upper quartile of visits in the 12 months prior to survey mailing. The study cohort had a mean age of 65 years and was largely male (95%), both consistent with a veteran population. After correcting for potential confounding factors through multivariable regression, the PCS was independently predictive of death, hospitalization, and high outpatient utilization. When using the first quartile of PCS as the reference population, those in the fourth quartile of PCS had a hazard ratio for death of 5.47 (95% confidence interval [CI], 3.63 to 8.26). Similarly, the odds ratios for hospitalization, high primary care visits, and high specialty medicine visits in the fourth quartile of PCS were 1.82 (95% CI, 1.51 to 2.19), 1.54 (95% CI, 1.26 to 1.87), and 1.46 (95% CI, 1.21 to 1.78), respectively. The MCS, through multivariable regression, was predictive of death but unassociated with subsequent hospitalization or high outpatient utilization. CONCLUSION: HRQL, as assessed by the SF-36V, is an independent predictor of mortality, hospitalization, and outpatient utilization in persons with self-reported obstructive lung disease.

Aged↗
PubMed2003

Efficacy trial of live, cold-adapted and inactivated influenza virus vaccines in older adults with chronic obstructive pulmonary disease: a VA cooperative study.

We assessed whether trivalent live, cold-adapted influenza virus (CAIV-T) vaccine provides added protection when co-administered with trivalent inactivated influenza virus vaccine (TVV) in patients with chronic obstructive pulmonary disease (COPD). Subjects (N=2215) were randomly assigned to receive either TVV intramuscularly (IM) and CAIV-T intranasally (TC), or TVV and placebo (TP). The vaccines were well-tolerated. Efficacy of TC compared to TP was not statistically significant and was 0.16 for any influenza virus strain (95% confidence limit (CL): -0.22, 0.43), 0.26 for A (H3N2) virus (95% CL: -0.17, 0.53), and -0.05 for type B virus (95% CL: -1.13, 0.48). However, there was a possible advantage for TC over TP in reducing respiratory consequences of an influenza season measured by pulmonary function and symptoms at end of study.

Administration, Intranasal↗
PubMed2003

Cost benefit of influenza vaccination in healthy, working adults: an economic analysis based on the results of a clinical trial of trivalent live attenuated influenza virus vaccine.

INTRODUCTION: Trivalent, intranasal, live attenuated influenza virus vaccine (LAIV) is safe and clinically effective in healthy, working adults. However, the potential economic benefits of vaccinating this population are still uncertain. We therefore conducted a cost benefit analysis of influenza vaccination of healthy working adults utilizing clinical outcome data from a trial of LAIV in healthy working adults. METHODS: This cost benefit analysis was based on the results of a multi-center, randomized, double blind placebo controlled trial that assessed the clinical effectiveness of LAIV in healthy working adults. Outcomes from the trial that were included in the cost benefit analysis were days of work missed, days working but at reduced effectiveness, and days with a health care provider visit due to at least one of the following symptoms: fever, runny nose, sore throat, cough, headache, muscle aches, chills, or tiredness/weakness. Cost data were obtained from nationally representative databases. Probability distributions for the key model variables were defined, and Monte Carlo simulation was used to estimate the mean break even costs for vaccine and its administration. Sensitivity analyses explored how changes in the variables affected these estimates. RESULTS: There were 4561 participants in the clinical trial. LAIV lowered work loss due to illness symptoms by 18% (relative rate [RR] 0.82, 95% confidence interval [CI] 0.74-0.91), days of working at reduced effectiveness by 18% (RR 0.82, 95% CI 0.74-0.91), and days with a health care provider visit by 13% (RR 0.87, 95% CI 0.77-0.98). The mean break even cost for vaccine and its administration was 43.07 US dollars per person vaccinated (5-95% percentiles, 25.72-58.92 US dollars). Major cost drivers were hourly wage and vaccine effectiveness in reducing productivity losses and health care use. CONCLUSION: This cost benefit analysis based on the results of the LAIV trial provides additional evidence that influenza vaccination may provide both health and economic benefits for healthy, working adults.

Absenteeism↗
PubMed2003

The efficacy, effectiveness and cost-effectiveness of inactivated influenza virus vaccines.

Influenza is a major cause of morbidity and mortality worldwide. Currently available inactivated influenza virus vaccines are safe and effective in preventing influenza. Substantial health benefits are seen across all age and risk groups. Studies assessing the economic benefits of vaccination suggest that vaccination is highly cost effective and in many cases cost saving among the elderly. Influenza vaccination has also been associated with significant economic benefits in younger adults and children. Additional health economic studies from developing countries and from tropical/subtropical regions will be vitally important for better understanding of the global burden of influenza and potential benefits of vaccination.

Adult↗
PubMed2003

Influenza vaccination and reduction in hospitalizations for cardiac disease and stroke among the elderly.

BACKGROUND: Upper respiratory tract illnesses have been associated with an increased risk of ischemic heart disease and stroke. During two influenza seasons, we assessed the influence of vaccination against influenza on the risk of hospitalization for heart disease and stroke, hospitalization for pneumonia and influenza, and death from all causes. METHODS: Cohorts of community-dwelling members of three large managed-care organizations who were at least 65 years old were studied during the 1998-1999 and 1999-2000 influenza seasons. Administrative and clinical data were used to evaluate outcomes, with multivariable logistic regression to control for base-line demographic and health characteristics of the subjects. RESULTS: There were 140,055 subjects in the 1998-1999 cohort and 146,328 in the 1999-2000 cohort, of which 55.5 percent and 59.7 percent, respectively, were immunized. At base line, vaccinated subjects were on average sicker, having higher rates of most coexisting conditions, outpatient care, and prior hospitalization for pneumonia than unvaccinated subjects. Unvaccinated subjects, however, were more likely to have been given a prior diagnosis of dementia or stroke. Vaccination against influenza was associated with a reduction in the risk of hospitalization for cardiac disease (reduction of 19 percent during both seasons [P<0.001]), cerebrovascular disease (reduction of 16 percent during the 1998-1999 season [P<0.018] and 23 percent during the 1999-2000 season [P<0.001]), and pneumonia or influenza (reduction of 32 percent during the 1998-1999 season [P<0.001] and 29 percent during the 1999-2000 season [P<0.001]) and a reduction in the risk of death from all causes (reduction of 48 percent during the 1998-1999 season [P<0.001] and 50 percent during the 1999-2000 season [P<0.001]). In analyses according to age, the presence or absence of major medical conditions at base line, and study site, the findings were consistent across all subgroups. CONCLUSIONS: In the elderly, vaccination against influenza is associated with reductions in the risk of hospitalization for heart disease, cerebrovascular disease, and pneumonia or influenza as well as the risk of death from all causes during influenza seasons. These findings highlight the benefits of vaccination and support efforts to increase the rates of vaccination among the elderly.

Aged↗
PubMed2003

Recognizing influenza in older patients with chronic obstructive pulmonary disease who have received influenza vaccine.

A substudy analysis was conducted to determine the clinical characteristics associated with symptomatic, laboratory-documented influenza (LDI) among 2215 veterans with chronic obstructive pulmonary disease who participated in Department of Veterans Affairs Cooperative Study 448 and who received trivalent inactivated influenza virus vaccine with or without intranasal live-attenuated, cold-adapted influenza vaccine. Of 585 evaluable first occurrences of acute respiratory illnesses, 94 (16%) were LDI. Respiratory symptoms of cough, sputum production, and dyspnea occurred in >90% of patients with LDI; 68% had documented or subjective fever, and 81% had myalgias. Stepwise logistic regression identified only fever and myalgia as being statistically associated with LDI. During the influenza outbreak period, the positive predictive value of fever and myalgia was 41%. Clinical criteria were poor predictors of LDI in these older, vaccinated patients with chronic lung disease. Additional studies are warranted to define optimal methods for the diagnosis of influenza among older persons with chronic obstructive pulmonary disease.

Aged↗
PubMed2002

Influence of high-risk medical conditions on the effectiveness of influenza vaccination among elderly members of 3 large managed-care organizations.

This serial cohort study assessed the risk of hospitalization or death associated with influenza and the effectiveness of influenza vaccination among subgroups of elderly members of 3 managed-care organizations in the United States. Data on baseline characteristics and outcomes were obtained from computerized databases. A total of 122,974 (1996-1997 season) and 158,454 (1997-1998 season) persons were included in the cohorts. Among unvaccinated persons, hospitalizations for pneumonia/influenza or death occurred in 8.2 of 1000 healthy and 38.4 of 1000 high-risk persons in year 1, and in 8.2 of 1000 healthy and 29.3 of 1000 high-risk persons in year 2. After adjustments, vaccination was associated with a 48% reduction in the incidence of hospitalization or death (95% confidence interval [CI], 42-52) in year 1 and 31% (95% CI, 26-37) in year 2. Effectiveness estimates were statistically significant and generally consistent across the healthy and high-risk subgroups. The absolute risk reduction, however, was 2.4- to 4.7-fold higher among high-risk than among healthy elderly persons. All elderly individuals may substantially benefit from vaccination. However, the impact of influenza is greater in persons with high-risk medical conditions.

Aged↗
PubMed2002

Cost effectiveness of influenza vaccination for healthy persons between ages 65 and 74 years.

Healthy persons between 65 and 74 years of age represent a large proportion of the population in this age group. Internationally, there is a substantial variation in whether these people are included among the recommendations for routine influenza vaccination. We therefore conducted this study, updating an earlier analysis, to assess the health and economic benefits of routine influenza vaccination of healthy persons between 65 and 74 years of age. The health benefits associated with vaccination were estimated using the administrative data bases of a large HMO in the Minneapolis, St. Paul, Minnesota area. Multivariate models were used to estimate reductions in hospitalization and death associated with vaccination. The economic analysis took the societal perspective and presented the results as net cost or saving per 10,000 persons vaccinated and per death prevented. Direct and indirect monetary costs were included in the models and were estimated from the published literature. Monte Carlo simulation was used to conduct probabilistic sensitivity analysis in order to derive probability intervals for each estimate of net costs or savings. Over the six consecutive study seasons, 1990-1991 to 1995-1996, vaccination of healthy elderly person was associated with a 36% reduction in hospitalization for pneumonia or influenza (95% CI, 2-39%), an 18% reduction in hospitalization for all respiratory conditions (95% CI, -6 to 37%) and a 40% reduction in death (95% CI, 14-38%). Vaccination was also associated with cost savings in all scenarios evaluated. The findings of this study again affirm the value of an age-based strategy for routine influenza vaccination of all elderly persons including healthy elderly persons between 65 and 74 years.

Aged↗
PubMed2002

Safety and acceptability of pneumococcal vaccinations administered in nontraditional settings.

BACKGROUND: Concerns about the safety and acceptability of vaccine administration in nontraditional settings might leave patients and their providers reluctant to take advantage of nontraditional settings for immunizations. METHODS: Elderly persons who received pneumococcal vaccinations in these settings were surveyed with a structured questionnaire. They were asked about local and systemic symptoms during the postvaccination week versus a comparison time period. RESULTS: Of the 1136 people included in the convenience sample, 636 responded (56%). Systemic symptoms were generally at similar or lower rates for the postvaccination week versus the comparison week, although fever was more common during the postvaccination week (3% vs 0.3%; P <.01). After vaccination 23.1% had any local symptom (soreness, redness, or swelling). Subjects who had been previously vaccinated were more likely to report local redness or swelling than were first-time vaccine recipients or people who were unsure of their vaccination status (13.1% vs 4.4% vs 1.4%, respectively; P =.001). In multivariate analyses, local symptoms were strongly associated with fever after vaccination (adjusted odds ratio, 13.15; P <.001), and revaccination was strongly associated with local symptoms (adjusted odds ratio, 3.77; P <.001). One hundred percent of respondents were very or somewhat satisfied with their experience, and >99% would recommend a nontraditional setting to a friend or family member. CONCLUSION: Nontraditional settings offer a safe and highly satisfactory option for the administration of pneumococcal vaccinations to the elderly.

Aged↗
PubMed2002

Immunization for seniors.

Vaccine-preventable diseases remain a significant health problem for adults in the United States. Far more adults die from the complications of vaccine-preventable diseases than do children in this country. Available vaccines that are effective in preventing morbidity and mortality from these conditions are underutilized, and significant racial and ethnic disparities in rates of utilization of adult vaccines persist. A variety of important vaccine-preventable diseases affect seniors. However, influenza and pneumococcal infections stand out as being responsible for more cases and more deaths each year among seniors than all other vaccine-preventable diseases in the United States combined. Current vaccination rates for these two diseases are far short of the Healthy People 2010 target rates of 90% immunization of the population of adults aged 65 years or over. Despite state efforts to improve vaccination rates of seniors, efforts that have included regulatory and educational approaches, significant challenges remain in designing immunization programs for seniors that are universally effective.

Black or African American↗