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Rosenbloom DIS, Dudášová J, Davis C, Railkar RA, Mehrotra N, Sachs JR. Replicate Testing of Clinical Endpoints Can Prevent No-Go Decisions for Beneficial Vaccines. Vaccines (Basel) 2023; 11:1501. [PMID: 37766177 PMCID: PMC10535203 DOI: 10.3390/vaccines11091501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 09/05/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
In vaccine efficacy trials, inaccurate counting of infection cases leads to systematic under-estimation-or "dilution"-of vaccine efficacy. In particular, if a sufficient fraction of observed cases are false positives, apparent efficacy will be greatly reduced, leading to unwarranted no-go decisions in vaccine development. Here, we propose a range of replicate testing strategies to address this problem, considering the additional challenge of uncertainty in both infection incidence and diagnostic assay specificity/sensitivity. A strategy that counts an infection case only if a majority of replicate assays return a positive result can substantially reduce efficacy dilution for assays with non-systematic (i.e., "random") errors. We also find that a cost-effective variant of this strategy, using confirmatory assays only if an initial assay is positive, yields a comparable benefit. In clinical trials, where frequent longitudinal samples are needed to detect short-lived infections, this "confirmatory majority rule" strategy can prevent the accumulation of false positives from magnifying efficacy dilution. When widespread public health screening is used for viruses, such as SARS-CoV-2, that have non-differentiating features or may be asymptomatic, these strategies can also serve to reduce unneeded isolations caused by false positives.
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Affiliation(s)
- Daniel I. S. Rosenbloom
- Quantitative Pharmacology and Pharmacometrics, Merck & Co., Inc., Rahway, NJ 07065, USA; (D.I.S.R.); (C.D.); (N.M.)
| | - Julie Dudášová
- Quantitative Pharmacology and Pharmacometrics, MSD Czech Republic, 15000 Prague, Czech Republic
- First Faculty of Medicine, Charles University, 12108 Prague, Czech Republic
| | - Casey Davis
- Quantitative Pharmacology and Pharmacometrics, Merck & Co., Inc., Rahway, NJ 07065, USA; (D.I.S.R.); (C.D.); (N.M.)
| | - Radha A. Railkar
- Biostatistics and Research Decision Sciences, Merck & Co., Inc., Rahway, NJ 07065, USA
| | - Nitin Mehrotra
- Quantitative Pharmacology and Pharmacometrics, Merck & Co., Inc., Rahway, NJ 07065, USA; (D.I.S.R.); (C.D.); (N.M.)
| | - Jeffrey R. Sachs
- Quantitative Pharmacology and Pharmacometrics, Merck & Co., Inc., Rahway, NJ 07065, USA; (D.I.S.R.); (C.D.); (N.M.)
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Plumb ID, Feldstein LR, Barkley E, Posner AB, Bregman HS, Hagen MB, Gerhart JL. Effectiveness of COVID-19 mRNA Vaccination in Preventing COVID-19-Associated Hospitalization Among Adults with Previous SARS-CoV-2 Infection - United States, June 2021-February 2022. MMWR. MORBIDITY AND MORTALITY WEEKLY REPORT 2022; 71:549-555. [PMID: 35421077 PMCID: PMC9020856 DOI: 10.15585/mmwr.mm7115e2] [Citation(s) in RCA: 66] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Previous infection with SARS-CoV-2, the virus that causes COVID-19, has been estimated to confer up to 90% protection against reinfection, although this protection was lower against the Omicron variant compared with that against other SARS-CoV-2 variants (1-3). A test-negative design was used to estimate effectiveness of COVID-19 mRNA vaccines in preventing subsequent COVID-19-associated hospitalization among adults aged ≥18 years with a previous positive nucleic acid amplification test (NAAT) or diagnosis of COVID-19.† The analysis used data from Cosmos, an electronic health record (EHR)-aggregated data set (4), and compared vaccination status of 3,761 case-patients (positive NAAT result associated with hospitalization) with 7,522 matched control-patients (negative NAAT result). After previous SARS-CoV-2 infection, estimated vaccine effectiveness (VE) against COVID-19-associated hospitalization was 47.5% (95% CI = 38.8%-54.9%) after 2 vaccine doses and 57.8% (95% CI = 32.1%-73.8%) after a booster dose during the Delta-predominant period (June 20-December 18, 2021), and 34.6% (95% CI = 25.5%-42.5%) after 2 doses and 67.6% (95% CI = 61.4%-72.8%) after a booster dose during the Omicron-predominant period (December 19, 2021-February 24, 2022). Vaccination provides protection against COVID-19-associated hospitalization among adults with previous SARS-CoV-2 infection, with the highest level of protection conferred by a booster dose. All eligible persons, including those with previous SARS-CoV-2 infection, should stay up to date with vaccination to prevent COVID-19-associated hospitalization.
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Hong K, Sohn S, Choe YJ, Rhie K, Lee JK, Han MS, Chun BC, Choi EH. Waning Effectiveness of One-dose Universal Varicella Vaccination in Korea, 2011-2018: a Propensity Score Matched National Population Cohort. J Korean Med Sci 2021; 36:e222. [PMID: 34519184 PMCID: PMC8438188 DOI: 10.3346/jkms.2021.36.e222] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 07/25/2021] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Despite high coverage (~98%) of universal varicella vaccination (UVV) in the Republic of Korea since 2005, reduction in the incidence rate of varicella is not obvious. The study aimed to evaluate the vaccine effectiveness (VE) of one-dose UVV by timeline and severity of the disease. METHODS All children born in Korea in 2011 were included for this retrospective cohort study that analyzed insurance claims data from 2011-2018 and the varicella vaccination records in the immunization registry. Adjusted hazard ratios by Cox proportional hazard models were used to estimate the VE through propensity score matching by the month of birth, sex, healthcare utilization rate, and region. RESULTS Of the total 421,070 newborns in the 2011 birth cohort, 13,360 were matched for age, sex, healthcare utilization rate, and region by the propensity score matching method. A total of 55,940 (13.29%) children were diagnosed with varicella, with the incidence rate 24.2 per 1000 person-year; 13.4% of vaccinated children and 10.4% of unvaccinated children. The VE of one-dose UVV against any varicella was 86.1% (95% confidence interval [CI], 81.4-89.5) during the first year after vaccination and 49.9% (95% CI, 43.3-55.7) during the 6-year follow-up period since vaccination, resulting in a 7.2% annual decrease of VE. The overall VE for severe varicella was 66.3%. The VE of two-dose compared to one-dose was 73.4% (95% CI, 72.2-74.6). CONCLUSION We found lower long-term VE in one-dose vaccination and waning of effectiveness over time. Longer follow ups of the vaccinated children as well as appropriately designed studies are needed to establish the optimal strategy in preventing varicella in Korea.
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Affiliation(s)
- Kwan Hong
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, Korea
| | - Sangho Sohn
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, Korea
| | - Young June Choe
- Department of Pediatrics, Korea University Anam Hospital, Seoul, Korea
| | - Kyuyol Rhie
- Department of Pediatrics, Incheon Sejong Hospital, Incheon, Korea
| | - Joon Kee Lee
- Department of Pediatrics, Chungbuk National University Hospital, Cheongju, Korea
| | - Mi Seon Han
- Department of Pediatrics, Seoul Metropolitan Government - Seoul National University Boramae Medical Center, Seoul, Korea
| | - Byung Chul Chun
- Department of Preventive Medicine, Korea University College of Medicine, Seoul, Korea
| | - Eun Hwa Choi
- Department of Pediatrics, Seoul National University Hospital, Seoul, Korea
- Department of Pediatrics, Seoul National University Hospital, Seoul, Korea.
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4
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So HY, Thompson ME, Wu C. Correlated and misclassified binary observations in complex surveys. CAN J STAT 2020. [DOI: 10.1002/cjs.11551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hon Yiu So
- Department of Statistics and Actuarial Science University of Waterloo Waterloo Ontario Canada N2L3G1
| | - Mary E. Thompson
- Department of Statistics and Actuarial Science University of Waterloo Waterloo Ontario Canada N2L3G1
| | - Changbao Wu
- Department of Statistics and Actuarial Science University of Waterloo Waterloo Ontario Canada N2L3G1
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5
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Estimating influenza vaccine effectiveness using data routinely available in electronic primary care records. Vaccine 2019; 37:755-762. [DOI: 10.1016/j.vaccine.2018.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 11/20/2018] [Accepted: 12/04/2018] [Indexed: 12/22/2022]
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Ito K, Mugitani A, Irie S, Ishibashi M, Takasaki Y, Shindo S, Yokoyama T, Yamashita Y, Shibao K, Koyanagi H, Fukushima W, Ohfuji S, Maeda A, Kase T, Hirota Y. Prior vaccinations improve immunogenicity of inactivated influenza vaccine in young children aged 6 months to 3 years: A cohort study. Medicine (Baltimore) 2018; 97:e11551. [PMID: 30024549 PMCID: PMC6086539 DOI: 10.1097/md.0000000000011551] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 06/22/2018] [Indexed: 11/25/2022] Open
Abstract
In young children, infrequent antigen exposure, which is partly characterized by fewer vaccinations, may be a factor impairing the immunogenicity of inactivated influenza vaccine.We assessed the effects of prior vaccinations on age-specific immune responses in Japanese children aged 6 months to 3 years, using data from a cohort study with 266 children who had received 2 doses (0.25 mL/dose for < 3 years old, 0.5 mL/dose for 3 years old) in the 2006/2007 season. Serological measures, primarily seroprotection rates, between previously vaccinated and vaccine-naïve children were compared within 1-year age strata. The seroprotection rate was defined in 2 ways as the proportion of subjects who achieved an antibody titer of 1:40 or 1:160. Multivariate logistic regression was also performed to estimate the independent effect of prior vaccination on seroprotection rate.After the first dose, seroprotection rates with the threshold of 1:40 in vaccine-naïve 1-year-olds remained low (28% for AH1, 26% for AH3, 2% for B), similar to those of 0-year-olds. In contrast, seroprotection rates in previously vaccinated 1-year-olds (77% for AH1, 86% for AH3, 18% for B) were significantly higher than those in vaccine-naïve 1-year-olds. These seroprotection rates for AH1 and AH3 were comparable with those in previously vaccinated 2- and 3-year-olds. Although seroprotection rates for B remained low in every age stratum even after the second dose, seroprotection rate in previously vaccinated 1-year-olds (50%) was similar to that in 3-year-olds. After adjustment for age, baseline antibody titer and experience of acute febrile respiratory illness in the preceding season, odds ratios showed a significant independent positive effect of prior vaccination on seroprotection rate for every strain. After the seroprotection threshold was changed from 1:40 to 1:160, the results of the effects of prior vaccinations on immunogenicity were similar or became more evident, which demonstrate the robustness of our findings.Our study found that prior vaccinations improved poor immunogenicity among young children, especially in 1-year-olds.
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Affiliation(s)
- Kazuya Ito
- Department of Public Health, Osaka City University Graduate School of Medicine; Research Center for Infectious Disease Sciences, Osaka City University Graduate School of Medicine, Osaka
- SOUSEIKAI Clinical Epidemiology Research Center
- College of Healthcare Management, Fukuoka
| | | | | | | | | | | | | | | | | | | | - Wakaba Fukushima
- Department of Public Health, Osaka City University Graduate School of Medicine; Research Center for Infectious Disease Sciences, Osaka City University Graduate School of Medicine, Osaka
| | - Satoko Ohfuji
- Department of Public Health, Osaka City University Graduate School of Medicine; Research Center for Infectious Disease Sciences, Osaka City University Graduate School of Medicine, Osaka
| | - Akiko Maeda
- Department of Public Health, Osaka City University Graduate School of Medicine; Research Center for Infectious Disease Sciences, Osaka City University Graduate School of Medicine, Osaka
| | - Tetsuo Kase
- Department of Public Health, Osaka City University Graduate School of Medicine; Research Center for Infectious Disease Sciences, Osaka City University Graduate School of Medicine, Osaka
| | - Yoshio Hirota
- SOUSEIKAI Clinical Epidemiology Research Center
- College of Healthcare Management, Fukuoka
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De Smedt T, Merrall E, Macina D, Perez-Vilar S, Andrews N, Bollaerts K. Bias due to differential and non-differential disease- and exposure misclassification in studies of vaccine effectiveness. PLoS One 2018; 13:e0199180. [PMID: 29906276 PMCID: PMC6003693 DOI: 10.1371/journal.pone.0199180] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 06/01/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Studies of vaccine effectiveness (VE) rely on accurate identification of vaccination and cases of vaccine-preventable disease. In practice, diagnostic tests, clinical case definitions and vaccination records often present inaccuracies, leading to biased VE estimates. Previous studies investigated the impact of non-differential disease misclassification on VE estimation. METHODS We explored, through simulation, the impact of non-differential and differential disease- and exposure misclassification when estimating VE using cohort, case-control, test-negative case-control and case-cohort designs. The impact of misclassification on the estimated VE is demonstrated for VE studies on childhood seasonal influenza and pertussis vaccination. We additionally developed a web-application graphically presenting bias for user-selected parameters. RESULTS Depending on the scenario, the misclassification parameters had differing impacts. Decreased exposure specificity had greatest impact for influenza VE estimation when vaccination coverage was low. Decreased exposure sensitivity had greatest impact for pertussis VE estimation for which high vaccination coverage is typically achieved. The impact of the exposure misclassification parameters was found to be more noticeable than that of the disease misclassification parameters. When misclassification is limited, all study designs perform equally. In case of substantial (differential) disease misclassification, the test-negative design performs worse. CONCLUSIONS Misclassification can lead to significant bias in VE estimates and its impact strongly depends on the scenario. We developed a web-application for assessing the potential (joint) impact of possibly differential disease- and exposure misclassification that can be modified by users to their own study scenario. Our results and the simulation tool may be used to guide better design, conduct and interpretation of future VE studies.
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Affiliation(s)
- Tom De Smedt
- P95 Epidemiology and Pharmacovigilance, Leuven, Belgium
| | | | | | - Silvia Perez-Vilar
- FISABIO-Public Health, Valencia, Spain
- Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Nick Andrews
- Statistics, Modelling, and Economics Department, Public Health England, Colindale, London, United Kingdom
| | - Kaatje Bollaerts
- P95 Epidemiology and Pharmacovigilance, Leuven, Belgium
- * E-mail:
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8
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Basic principles of test-negative design in evaluating influenza vaccine effectiveness. Vaccine 2018; 35:4796-4800. [PMID: 28818471 DOI: 10.1016/j.vaccine.2017.07.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 04/20/2017] [Accepted: 05/31/2017] [Indexed: 11/20/2022]
Abstract
Based on the unique characteristics of influenza, the concept of "monitoring" influenza vaccine effectiveness (VE) across the seasons using the same observational study design has been developed. In recent years, there has been a growing number of influenza VE reports using the test-negative design, which can minimize both misclassification of diseases and confounding by health care-seeking behavior. Although the test-negative designs offer considerable advantages, there are some concerns that widespread use of the test-negative design without knowledge of the basic principles of epidemiology could produce invalid findings. In this article, we briefly review the basic concepts of the test-negative design with respect to classic study design such as cohort studies or case-control studies. We also mention selection bias, which may be of concern in some countries where rapid diagnostic testing is frequently used in routine clinical practices, as in Japan.
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Schwartz KL, Tu K, Wing L, Campitelli MA, Crowcroft NS, Deeks SL, Wilson SE, Wilson K, Gemmill I, Kwong JC. Validation of infant immunization billing codes in administrative data. Hum Vaccin Immunother 2016; 11:1840-7. [PMID: 26075651 PMCID: PMC4514409 DOI: 10.1080/21645515.2015.1043499] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Ontario has a single payer provincial health insurance program. Administrative data may provide a potentially robust source of information for post-marketing vaccine studies. Vaccine-specific immunization billing codes were introduced in 2011. Our objective was to validate Ontario's universal health care administrative datasets to assess infant immunization status. Electronic medical record data from the Electronic Medical Record Administrative data Linked Database (EMRALD) was used as the reference standard to calculate performance characteristics of the Ontario Health Insurance Plan (OHIP) database vaccine-specific and general immunization codes for 4 primary infant immunizations: diphtheria, tetanus, acellular pertussis, inactivated polio, Haemophilus influenzae type B (DTaP-IPV-Hib) combination vaccine, pneumococcal conjugate vaccine, measles, mumps, rubella (MMR) vaccine, and meningococcal conjugate serogroup C vaccine. OHIP billing claims had specificity ranging from 81% to 92%, sensitivity 70% to 83%, positive predictive value (PPV) 97% to 99%, and negative predictive value (NPV) 13% to 46% for identifying the various specific vaccines in administrative data. For cohorts vaccinated in the new code introduction phase, using both the vaccine-specific and general codes had higher sensitivity than the vaccine-specific codes alone. In conclusion, immunization billing claims from administrative data in Ontario had high specificity and PPV, moderate sensitivity, and low NPV. This study identifies some of the applications of utilizing administrative data for post-marketing vaccine studies. However, limitations of these data decrease their utility for measuring vaccine coverage and effectiveness. Therefore, the establishment of a comprehensive and linkable immunization registry should be a provincial priority.
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Key Words
- CIC, Citizen and Immigration Canada
- CIHI-DAD, Canadian Institute of Health Information Discharge Abstract Database
- COC, continuity of care
- DTaP-IPV-Hib, diphtheria, tetanus, acellular pertussis, inactivated polio, Haemophilus influenzae type B vaccine
- EMR, electronic medical records
- EMRALD, Electronic Medical Record Administrative data Linked Database
- ICES, Institute for Clinical Evaluative Sciences
- MMR, measles, mumps, rubella vaccine
- MenC, meningococcal conjugate serogroup C vaccine
- NPV, negative predictive value
- OHIP, Ontario Health Insurance Plan
- PC, pneumococcal conjugate vaccine
- PPV, positive predictive value
- RPDB, Registered Persons Database
- diphtheria-tetanus-pertussis vaccine
- health services
- measles-mumps-rubella vaccine
- meningococcal vaccines
- pneumococcal vaccines
- vaccine combined
- validation studies
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Affiliation(s)
- Kevin L Schwartz
- a Institute for Clinical Evaluative Sciences ; Toronto , Ontario , Canada
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Hara M, Hanaoka T, Maeda K, Kase T, Ohfuji S, Fukushima W, Hirota Y. Immunogenicity and Efficacy of A/H1N1pdm Vaccine Among Subjects With Severe Motor and Intellectual Disability in the 2010/11 Influenza Season. J Epidemiol 2016; 26:300-6. [PMID: 26780860 PMCID: PMC4884898 DOI: 10.2188/jea.je20150036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background While the immunogenicity and effectiveness of seasonal influenza vaccines among subjects with severe motor and intellectual disability (SMID) are known to be diminished, the efficacy of the A/H1N1pdm vaccine has not been evaluated. Methods We prospectively evaluated 103 subjects with SMID (mean age, 41.7 years) who received trivalent inactivated influenza vaccine during the 2010/11 influenza season. The hemagglutination inhibition (HI) antibody titer was measured in serum samples collected pre-vaccination (S0), post-vaccination (S1), and end-of-season (S2) to evaluate subjects’ immunogenicity capacity. Vaccine efficacy was assessed based on antibody efficacy and achievement proportion. Results The proportions of seroprotection and seroconversion, and the geometric mean titer (GMT) ratio (GMT at S1/GMT at S0) for A/H1N1pdm were 46.0%, 16.0%, and 1.8, respectively—values which did not meet the European Medicines Evaluation Agency criteria. The achievement proportion was 26%. During follow-up, 11 of 43 subjects with acute respiratory illness were diagnosed with type A influenza according to a rapid influenza diagnostic test (RIDT), and A/H1N1pdm strains were isolated from the throat swabs of 5 of those 11 subjects. When either or both RIDT-diagnosed influenza or serologically diagnosed influenza (HI titer at S2/HI titer at S1 ≥2) were defined as probable influenza, subjects with A/H1N1pdm seroprotection were found to have a lower incidence of probable influenza (odds ratio, 0.31; antibody efficacy, 69%; vaccine efficacy, 18%). Conclusions In the present seasonal assessment, antibody efficacy was moderate against A/H1N1pdm among SMID subjects, but vaccine efficacy was low due to the reduced immunogenicity of SMID subjects.
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Affiliation(s)
- Megumi Hara
- Department of Preventive Medicine, Faculty of Medicine, Saga University
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11
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Nakata K, Fujieda M, Miki H, Fukushima W, Ohfuji S, Maeda A, Kase T, Hirota Y. Detection of influenza vaccine effectiveness among nursery school children: Lesson from a season with cocirculating respiratory syncytial virus. Hum Vaccin Immunother 2015; 11:545-52. [PMID: 25714791 DOI: 10.1080/21645515.2015.1011982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In the winter influenza epidemic season, patients with respiratory illnesses including respiratory syncytial virus (RSV) infections increase among young children. Therefore, we evaluated the effectiveness of influenza vaccine against influenza-like illness (ILI) using a technique to identify outbreaks of RSV infection and to distinguish those patients from ILI patients. The study subjects were 101 children aged 12 to 84 months attending nursery school. We classified the cases into 6 levels based on the definitions of ILI for outcomes. We established observation periods according to information obtained from regional surveillance and rapid diagnostic tests among children. Multivariate odds ratios (ORs) for each case classification were obtained using a logistic regression model for each observation period. For the entire observation period, ORs for cases with fever plus respiratory symptoms were reduced marginally significantly. For the local influenza epidemic period, only the OR for the most serious cases was significantly decreased (0.20 [95%CI: 0.04-0.94]). During the influenza outbreak among the nursery school children, multivariate ORs for fever plus respiratory symptoms decreased significantly (≥ 38.0°C plus ≥ one symptoms: 0.23 [0.06-0.91), ≥ 38.0°C plus ≥ 2 symptoms: 0.21 [0.05-0.85], ≥ 39.0°C plus ≥ one symptoms: 0.18 [0.04-0.93] and ≥ 39.0°C plus ≥ 2 symptoms: 0.16 [0.03-0.87]). These results suggest that confining observation to the peak influenza epidemic period and adoption of a strict case classification system can minimize outcome misclassification when evaluating the effectiveness of influenza vaccine against ILI, even if influenza and RSV cocirculate in the same season.
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Affiliation(s)
- Keiko Nakata
- a Department of Public Health ; Osaka City University Graduate School of Medicine ; Osaka , Japan
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12
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Bolin JH, Finch WH. Supervised classification in the presence of misclassified training data: a Monte Carlo simulation study in the three group case. Front Psychol 2014; 5:118. [PMID: 24616711 PMCID: PMC3937587 DOI: 10.3389/fpsyg.2014.00118] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 01/28/2014] [Indexed: 11/15/2022] Open
Abstract
Statistical classification of phenomena into observed groups is very common in the social and behavioral sciences. Statistical classification methods, however, are affected by the characteristics of the data under study. Statistical classification can be further complicated by initial misclassification of the observed groups. The purpose of this study is to investigate the impact of initial training data misclassification on several statistical classification and data mining techniques. Misclassification conditions in the three group case will be simulated and results will be presented in terms of overall as well as subgroup classification accuracy. Results show decreased classification accuracy as sample size, group separation and group size ratio decrease and as misclassification percentage increases with random forests demonstrating the highest accuracy across conditions.
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Affiliation(s)
- Jocelyn Holden Bolin
- Department of Educational Psychology, Teachers College, Ball State University Muncie, IN, USA
| | - W Holmes Finch
- Department of Educational Psychology, Teachers College, Ball State University Muncie, IN, USA
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13
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Wiley DJ, Li X, Hsu H, Seaberg EC, Cranston RD, Young S, D’Souza G, Martínez-Maza O, DeAzambuja K, Chua K, Hussain SK, Detels R. Factors affecting the prevalence of strongly and weakly carcinogenic and lower-risk human papillomaviruses in anal specimens in a cohort of men who have sex with men (MSM). PLoS One 2013; 8:e79492. [PMID: 24278140 PMCID: PMC3835810 DOI: 10.1371/journal.pone.0079492] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 09/22/2013] [Indexed: 02/06/2023] Open
Abstract
Background MSM are at higher risk for invasive anal cancer. Twelve human papillomaviruses (HPVs) cause cervical cancer in women (Group 1 high-risk HPVs (hrHPVs)) and 13 HPVs are probable/possible causes (Group 2 hrHPVs) of cervical malignancy. HPVs rarely associated with malignancy are classified as lower-risk HPVs (lrHPVs). Materials and Methods Dacron-swab anal-cytology specimens were collected from and data complete for 97% (1262/1296) of Multicenter AIDS Cohort Study (MACS) men tested for HPVs using the Linear Array assay. Multivariate Poisson regression analyses estimated adjusted prevalence ratios for Group 1/2 hrHPVs and lrHPVs, controlling for the effects of age, race, ethnicity, sexual partnerships, smoking; HIV-infection characteristics, treatment, and immune status among HIV-infected men. Results HIV-infected men showed 35–90% higher prevalence of Group 1/2 hrHPVs and lrHPVs than HIV-uninfected men, and higher prevalence of multi-Type, and multiple risk-group infections. CD4+ T-cell count was inversely associated with HPV Group 2 prevalence (p<0.0001). The number of receptive anal intercourse (RAI) partners reported in the 24 months preceding HPV testing predicted higher prevalence of Group 1/2 hrHPVs. Men reporting ≥30 lifetime male sex partners before their first MACS visit and men reporting ≥1 RAI partners during the 24 months before HPV testing showed 17–24% and 13–17% higher prevalence of lrHPVs (p-values ≤0.05). Men reporting smoking between MACS visit 1 and 24 months before HPV testing showed 1.2-fold higher prevalence of Group 2 hrHPVs (p = 0.03). Both complete adherence to CART (p = 0.02) and HIV load <50 copies/mL (p = 0.04) were protective for Group 1 hrHPVs among HIV-infected men. Conclusions HIV-infected men more often show multi-type and multi-group HPV infections HIV-uninfected men. Long-term mutual monogamy and smoking cessation, generally, and CART-adherence that promotes (HIV) viremia control and prevents immunosuppression, specifically among HIV-infected MSM, are important prevention strategies for HPV infections that are relevant to anal cancer.
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Affiliation(s)
- Dorothy J. Wiley
- School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
| | - Xiuhong Li
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Hilary Hsu
- School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America
| | - Eric C. Seaberg
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Ross D. Cranston
- School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Stephen Young
- Tricore Diagnostic Laboratories, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Gypsyamber D’Souza
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Otoniel Martínez-Maza
- David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America
- UCLA AIDS Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Katherine DeAzambuja
- School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America
| | - Kristofer Chua
- School of Nursing, University of California Los Angeles, Los Angeles, California, United States of America
| | - Shehnaz K. Hussain
- Jonathan and Karen Fielding School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America
| | - Roger Detels
- Jonathan and Karen Fielding School of Public Health, University of California Los Angeles, Los Angeles, California, United States of America
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Rolnick SJ, Parker ED, Nordin JD, Hedblom BD, Wei F, Kerby T, Jackson JM, Crain AL, Euler G. Self-report compared to electronic medical record across eight adult vaccines: do results vary by demographic factors? Vaccine 2013; 31:3928-35. [PMID: 23806243 DOI: 10.1016/j.vaccine.2013.06.041] [Citation(s) in RCA: 186] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/10/2013] [Accepted: 06/12/2013] [Indexed: 10/26/2022]
Abstract
Immunizations are crucial to the prevention of disease, thus, having an accurate measure of vaccination status for a population is an important guide in targeting prevention efforts. In order to comprehensively assess the validity of self-reported adult vaccination status for the eight most common adult vaccines we conducted a survey of vaccination receipt and compared it to the electronic medical record (EMR), which was used as the criterion standard, in a population of community-dwelling patients in a large healthcare system. In addition, we assessed whether validity varied by demographic factors. The vaccines included: pneumococcal (PPSV), influenza (Flu), tetanus diphtheria (Td), tetanus diphtheria pertussis (Tdap), Human Papilloma Virus (HPV), hepatitis A (HepA), hepatitis B (HepB) and herpes zoster (shingles). Telephone surveys were conducted with 11,760 individuals, ≥18, half with documented receipt of vaccination and half without. We measured sensitivity, specificity, positive and negative predictive value, net bias and over- and under-reporting of vaccination. Variation was found across vaccines, however, sensitivity and specificity did not vary substantially by either age or race/ethnicity. Sensitivity ranged between 63% for HepA to over 90% (tetanus, HPV, shingles and Flu). Hispanics were 2.7 times more likely to claim receipt of vaccination compared to whites. For PPSV and Flu those 65+ had low specificity compared to patients of younger ages while those in the youngest age group had lowest specificity for HepA and HepB. In addition to racial/ethnic differences, over-reporting was more frequent in those retired and those with household income less than $75,000. Accurate information for vaccination surveillance is important to estimate progress toward vaccination coverage goals and ensure appropriate policy decisions and allocation of resources for public health. It was clear from our findings that EMR and self-report do not always agree. Finding approaches to improve both EMR data capture and patient awareness would be beneficial.
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Affiliation(s)
- S J Rolnick
- HealthPartners Institute for Education & Research, P.O. Box 1524, Minneapolis, MN 55440-1524, USA.
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15
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Ramdas WD, Rizopoulos D, Wolfs RCW, Hofman A, de Jong PTVM, Vingerling JR, Jansonius NM. Defining glaucomatous optic neuropathy from a continuous measure of optic nerve damage - the optimal cut-off point for risk-factor analysis in population-based epidemiology. Ophthalmic Epidemiol 2011; 18:211-6. [PMID: 21961510 DOI: 10.3109/09286586.2011.595038] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Diseases characterized by a continuous trait can be defined by setting a cut-off point for the disease measure in question, accepting some misclassification. The 97.5th percentile is commonly used as a cut-off point. However, it is unclear whether this percentile is the optimal cut-off point from the point of view of risk-factor analysis. The optimal cut-off point for risk-factor analysis can be found with a statistical method that minimizes the effect of misclassification. We applied this method to glaucomatous optic neuropathy. Here, the continuous trait is the cup-disc ratio. The aim of this study was to determine the optimal cup-disc ratio cut-off point for risk-factor analysis in population-based epidemiology. METHODS All participants in the population-based Rotterdam Study underwent intraocular pressure (IOP) measurements, assessment of the cup-disc ratio with the Heidelberg Retina Tomograph (HRT) and visual field testing. In the statistical method, the cup-disc ratio (the continuous trait) and the IOP (a major risk factor) were independent variables and glaucomatous visual field loss (the true glaucoma endpoint) the dependent variable in a logistic regression model. The optimal cup-disc ratio cut-off point was found by minimizing the influence of IOP in this model. Variability of the approach was assessed by using a bootstrap resampling technique. RESULTS Of 2444 included participants, 93 had glaucomatous visual field loss. The median optimal cup-disc ratio cut-off point was the 97.0th percentile with a 95% central range from 95.5 to 98.5. CONCLUSION The optimal cup-disc ratio cut-off point for risk-factor analysis is close to the commonly used 97.5th percentile.
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Affiliation(s)
- Wishal D Ramdas
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
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16
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McCarthy NL, Gee J, Weintraub E, Donahue JG, Nordin JD, Daley MF, Naleway A, Henninger M, Baxter R, Crane B, Aukes L, Wagner N, Fisher S, Jacobsen SJ, Sy L, Baggs J. Monitoring vaccine safety using the Vaccine Safety Datalink: utilizing immunization registries for pandemic influenza. Vaccine 2011; 29:4891-6. [PMID: 21596088 DOI: 10.1016/j.vaccine.2011.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 11/20/2022]
Abstract
Mass vaccination campaigns during which new vaccines may be administered to many millions of people in a short period of time call for timely and accurate post-licensure surveillance to monitor vaccine safety. To address the need for timely H1N1 influenza vaccine safety information during the 2009-2010 H1N1 influenza pandemic, the Vaccine Safety Datalink (VSD) project assessed the feasibility and potential mechanisms for utilizing data from state and local immunization registries to capture vaccinations that would not otherwise be captured by the data systems of the participating VSD managed care organizations (MCOs). Three of the eight VSD sites were able to capture H1N1 immunization data electronically from the state and local registries, and one site was able to capture the immunizations through a paper-based system; however, the remaining four sites encountered various obstacles that prevented capture of such data. Additional work will be required at these sites to overcome the barriers, which included privacy and confidentiality laws, time constraints brought on by the pandemic, as well as data quality concerns.
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Affiliation(s)
- Natalie L McCarthy
- Centers for Disease Control and Prevention, 1600 Clifton Rd., MS-D26, Atlanta, GA 30333, USA.
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17
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Chen TM, Lin CC, Huang PT, Wen CF. Metformin associated with lower mortality in diabetic patients with early stage hepatocellular carcinoma after radiofrequency ablation. J Gastroenterol Hepatol 2011; 26:858-65. [PMID: 21251068 DOI: 10.1111/j.1440-1746.2011.06664.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIM Type 2 diabetes increases the risk of cancer development and mortality. However, antidiabetic treatment with metformin can reduce the risk of cancer. We studied whether metformin users among diabetic patients with early hepatocellular carcinoma (HCC) undergoing radiofrequency ablation (RFA) would have a favorable survival compared with those without metformin treatment. METHODS A total of 135 patients with early stage HCC having 162 tumors underwent RFA. Among them, 53 patients were diabetic, including 21 metformin users and 32 patients without metformin treatment. RESULTS Diabetic patients had an inferior survival rate compared with nondiabetic patients (1 year, 82.8% vs 93.9%; 3 years, 55.1% vs 80.2%; 5 years, 41.3% vs 64.7%; P = 0.004). With regards to antidiabetic treatments, metformin users had better survival outcome (adjusted hazard ratio [HR] 0.24; 95% confidence interval [CI], 0.07-0.80; P = 0.020) compared to patients without metformin treatment after adjustments for potential confounders. Sulfonylureas and insulin exposures did not achieve significant conclusions. For the whole studied population including nondiabetic and diabetic patients, the multivariate analysis revealed that maximum tumor size more than 2.5 cm (HR, 3.49; 95% CI, 1.74-6.99; P < 0.001) and diabetic patients without metformin treatment (HR, 3.34; 95% CI, 1.67-6.71, P = 0.001) were independent explanatory variables associated with unfavorable survival. CONCLUSIONS Metformin users among diabetic patients with HCC undergoing RFA had a favorable overall survival compared with patients without metformin treatment.
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Affiliation(s)
- Tsung-Ming Chen
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
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18
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Matsui D, Shigeta M, Ozasa K, Kuriyama N, Watanabe I, Watanabe Y. Factors associated with influenza vaccination status of residents of a rural community in Japan. BMC Public Health 2011; 11:149. [PMID: 21375758 PMCID: PMC3060116 DOI: 10.1186/1471-2458-11-149] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 03/04/2011] [Indexed: 11/25/2022] Open
Abstract
Background The rate of influenza vaccination in Japan has declined over the past several decades. It is essential to identify community-specific factors that affect attitudes toward vaccination, but such parameters have not yet been fully determined in Japan. The present study used the Health Belief Model (HBM) to identify perceptions of influenza vaccination in a rural Japanese community. Methods All subjects were residents of a rural town in the southern part of Kyoto, Japan. An anonymous self-administered questionnaire was mailed to 846 randomly chosen households (containing 2,665 subjects). The survey explored gender, age, history of influenza, and factors associated with obtaining influenza vaccination, based on the HBM. Results A total of 1,182 valid responses (response rate, 44.4%) were received. Sources of information that were associated with vaccination decisions were medical facilities for children (OR = 4.21; 95% CI: 1.17-15.1), workplaces for adults (OR = 2.40; 95% CI: 1.22-4.75), medical facilities, town office and family for elderly subjects (OR = 6.18; 95% CI: 2.42-15.7, OR = 5.59; 95% CI: 2.26-13.8 and OR = 3.29; 95%CI: 1.01-10.6). Subjects, in all age groups, who strongly agreed that the vaccine was effective were significantly more likely to be vaccinated (OR = 10.5; 95%CI: 2.68-41.7 for children; OR = 8.85; 95%CI: 4.61-16.9 for adults; OR = 19.9; 95%CI: 8.28-48.0 for the elderly). The vaccination rate of elderly subjects who expressed concerns regarding adverse vaccine effects (OR = 0.34, 95% CI: 0.15-0.78) or who were worried about practical barriers to the vaccination process (OR = 0.13; 95% CI: 0.05-0.31) was significantly lower than in other populations. Conclusions Our results indicate that vaccination coverage can be increased if accurate information on personal risk, severity of influenza illness, and efficacy of vaccination are provided by responsible information sources that are easily accessible. Such sources include medical facilities and municipal offices. In addition, barriers and inconveniences associated with vaccination should be removed, especially if they impact on elderly people.
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Affiliation(s)
- Daisuke Matsui
- Epidemiology for Community Health & Medicine, Graduate school of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
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19
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Evaluation of seasonal influenza vaccination effectiveness based on antibody efficacy among the institutionalized elderly in Japan. Vaccine 2010; 28:5664-8. [PMID: 20600482 DOI: 10.1016/j.vaccine.2010.06.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 06/09/2010] [Accepted: 06/20/2010] [Indexed: 11/22/2022]
Abstract
Influenza vaccination efficacy was evaluated in 114 institutionalized elderly people in 2002/03. Strain A/H3N2 was isolated; 44 and 8 subjects had sudden-onset fever (> or = 37.8 degrees C) and kit-diagnosed influenza, respectively. Odds ratios adjusted for age, sex, comorbidity, and vaccine strain (OR(adj)) were determined using multiple logistic regression. Seroprotected patients (haemagglutination-inhibition antibody titre > or = 1:40) had lower incidence of fever (OR(adj), 0.35; 95% confidence interval [CI], 0.09-1.28) and kit-diagnosed influenza (OR(adj), 0.35; 95% CI, 0.03-4.64) than patients without seroprotection (antibody efficacy, approximately 65%). Seroprotective levels of vaccination-induced antibodies probably prevent influenza among the institutionalized elderly, although statistical significance could not be confirmed owing to the sample size.
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Sy LS, Liu ILA, Solano Z, Cheetham TC, Lugg MM, Greene SK, Weintraub ES, Jacobsen SJ. Accuracy of influenza vaccination status in a computer-based immunization tracking system of a managed care organization. Vaccine 2010; 28:5254-9. [PMID: 20554065 DOI: 10.1016/j.vaccine.2010.05.061] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 05/06/2010] [Accepted: 05/26/2010] [Indexed: 12/01/2022]
Abstract
Influenza vaccine safety and effectiveness studies conducted using electronic medical records rely on accurate assessment of influenza vaccination status. However, influenza immunization in non-traditional settings (e.g., the workplace) may not be captured in patient immunization tracking systems. We compared influenza vaccination status from electronic records with self-reported vaccination status for five hundred and two 50-79 years olds enrolled in a large managed care organization. Influenza vaccination status in the medical record had a high positive predictive value and specificity (both >99%). The negative predictive value was 80% and sensitivity was 78%. These data suggest that an electronic record of influenza vaccination reliably indicates immunization, while the absence of such a record is only moderately accurate, partly due to vaccines received in non-traditional settings.
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Affiliation(s)
- Lina S Sy
- Kaiser Permanente Southern California, 100 South Los Robles Ave., Pasadena, CA 91101, USA.
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21
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Yamaguchi S, Ohfuji S, Hirota Y. Influenza vaccine effectiveness in primary school children in Japan: a prospective cohort study using rapid diagnostic test results. J Infect Chemother 2010; 16:407-13. [PMID: 20490595 DOI: 10.1007/s10156-010-0070-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 04/14/2010] [Indexed: 11/24/2022]
Abstract
A low-cost, prospective cohort study using the results of rapid diagnostic test performed at local clinics was conducted to estimate influenza vaccine effectiveness (VE) in school children (6-12 year-olds). All children in four primary schools in Tsuchiura City, Ibaraki, Japan were enrolled (n = 2607). Vaccination status and other risk factors were obtained with a baseline questionnaire. Participants were encouraged to visit a clinic to have a rapid test when they developed an influenza-like illness during the winter season in 2006-2007, and 88.6% of those who reported influenza to the school had been tested. The result of the test was obtained with another questionnaire. The attack rate of influenza A and B was 5.4% and 11.9%, respectively. Logistic regression was used to model the association between influenza vaccination and rapid-test-confirmed influenza after adjusting for potential confounders. Influenza VE was calculated as (1- adjusted odds ratio) × 100. VE for total influenza was 21% (95% confidence interval -8 to 42), which was a combination of VE for influenza A (44%, 8-66) and VE for influenza B (5%, -37 to 34). Among several possibilities that would account for rather low VE estimates in this study, low sensitivity of the rapid test, and differential propensity to seek vaccination or medical care between the vaccinated and nonvaccinated were considered to be important. This study was able to estimate influenza VE at very low cost with high specificity in case ascertainment by collecting the readily available data on influenza rapid test with questionnaires.
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Affiliation(s)
- Shinya Yamaguchi
- Department of Pediatrics, Kasumigaura Medical Center, 2-7-14 Shimotakatsu, Tsuchiura, Ibaraki 300-8585, Japan.
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Accuracy of data on influenza vaccination status at four Vaccine Safety Datalink sites. Am J Prev Med 2009; 37:552-5. [PMID: 19944924 DOI: 10.1016/j.amepre.2009.08.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 07/08/2009] [Accepted: 08/28/2009] [Indexed: 11/20/2022]
Abstract
BACKGROUND Studies of influenza vaccination using electronic medical records rely on accurate classification of vaccination status. Vaccinations not entered into electronic records would be unavailable for study. PURPOSE This study evaluated the sensitivity and negative predictive value (NPV) of electronic records for influenza vaccination and factors associated with failure to capture vaccinations. METHODS In four diverse medical care organizations in the Vaccine Safety Datalink, those aged 50-79 years with no influenza vaccination record during the 2007-2008 season were surveyed by telephone, and electronic records were analyzed in 2008. The sensitivity and NPV of electronic records were estimated, using survey responses as the gold standard. Logistic regression models determined associations between 1-NPV and demographic factors, risk of influenza complications, and healthcare utilization levels. RESULTS Data were obtained for 933 survey participants and 1,085,916 medical care organization members. Sites varied significantly in the sensitivity (51%, 68%, 79%, 89%) and NPV (46%, 62%, 66%, 87%) of electronic records. In multivariate analysis, the rate of failure to capture vaccinations was significantly higher for those aged 65-79 years than for those aged 50-64 years at three sites. Of vaccinations not captured by electronic records, 58% were reportedly administered in nontraditional settings, usually workplaces; the rest were given within the sites. CONCLUSIONS Influenza vaccination studies relying on electronic records may misclassify substantial proportions of vaccinated individuals as unvaccinated, producing biased estimates of vaccine effectiveness. Sites with limited sensitivity to capture vaccinations administered within their organization should seek possible remedies. More complete capture of vaccinations administered to older patients and in nontraditional settings would further reduce misclassification.
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Inactivated influenza vaccine effectiveness against influenza-like illness among young children in Japan—With special reference to minimizing outcome misclassification. Vaccine 2009; 27:7031-5. [DOI: 10.1016/j.vaccine.2009.09.067] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 09/07/2009] [Accepted: 09/16/2009] [Indexed: 11/23/2022]
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