Dataset Information

Reliability of Nationwide Prevalence Estimates of Dementia: A Critical Appraisal Based on Brazilian Surveys.

ABSTRACT:

Background

The nationwide dementia prevalence is usually calculated by applying the results of local surveys to countries' populations. To evaluate the reliability of such estimations in developing countries, we chose Brazil as an example. We carried out a systematic review of dementia surveys, ascertained their risk of bias, and present the best estimate of occurrence of dementia in Brazil.

Methods and findings

We carried out an electronic search of PubMed, Latin-American databases, and a Brazilian thesis database for surveys focusing on dementia prevalence in Brazil. The systematic review was registered at PROSPERO (CRD42014008815). Among the 35 studies found, 15 analyzed population-based random samples. However, most of them utilized inadequate criteria for diagnostics. Six studies without these limitations were further analyzed to assess the risk of selection, attrition, outcome and population bias as well as several statistical issues. All the studies presented moderate or high risk of bias in at least two domains due to the following features: high non-response, inaccurate cut-offs, and doubtful accuracy of the examiners. Two studies had limited external validity due to high rates of illiteracy or low income. The three studies with adequate generalizability and the lowest risk of bias presented a prevalence of dementia between 7.1% and 8.3% among subjects aged 65 years and older. However, after adjustment for accuracy of screening, the best available evidence points towards a figure between 15.2% and 16.3%.

Conclusions

The risk of bias may strongly limit the generalizability of dementia prevalence estimates in developing countries. Extrapolations that have already been made for Brazil and Latin America were based on a prevalence that should have been adjusted for screening accuracy or not used at all due to severe bias. Similar evaluations regarding other developing countries are needed in order to verify the scope of these limitations.

SUBMITTER: Chaimowicz F

PROVIDER: S-EPMC4488471 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Reliability of Nationwide Prevalence Estimates of Dementia: A Critical Appraisal Based on Brazilian Surveys.

Chaimowicz Flávio F Burdorf Alex A

PloS one 20150701 7

<h4>Background</h4>The nationwide dementia prevalence is usually calculated by applying the results of local surveys to countries' populations. To evaluate the reliability of such estimations in developing countries, we chose Brazil as an example. We carried out a systematic review of dementia surveys, ascertained their risk of bias, and present the best estimate of occurrence of dementia in Brazil.<h4>Methods and findings</h4>We carried out an electronic search of PubMed, Latin-American databas ...[more]

PMID: 26131563

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Project description:BACKGROUND:Population-based data on COVID-19 are essential for guiding policies. There are few such studies, particularly from low or middle-income countries. Brazil is currently a hotspot for COVID-19 globally. We aimed to investigate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody prevalence by city and according to sex, age, ethnicity group, and socioeconomic status, and compare seroprevalence estimates with official statistics on deaths and cases. METHODS:In this repeated cross-sectional study, we did two seroprevalence surveys in 133 sentinel cities in all Brazilian states. We randomly selected households and randomly selected one individual from all household members. We excluded children younger than 1 year. Presence of antibodies against SARS-CoV-2 was assessed using a lateral flow point-of-care test, the WONDFO SARS-CoV-2 Antibody Test (Wondfo Biotech, Guangzhou, China), using two drops of blood from finger prick samples. This lateral-flow assay detects IgG and IgM isotypes that are specific to the SARS-CoV-2 receptor binding domain of the spike protein. Participants also answered short questionnaires on sociodemographic information (sex, age, education, ethnicity, household size, and household assets) and compliance with physical distancing measures. FINDINGS:We included 25?025 participants in the first survey (May 14-21) and 31?165 in the second (June 4-7). For the 83 (62%) cities with sample sizes of more than 200 participants in both surveys, the pooled seroprevalence increased from 1·9% (95% CI 1·7-2·1) to 3·1% (2·8-3·4). City-level prevalence ranged from 0% to 25·4% in both surveys. 11 (69%) of 16 cities with prevalence above 2·0% in the first survey were located in a stretch along a 2000 km of the Amazon river in the northern region. In the second survey, we found 34 cities with prevalence above 2·0%, which included the same 11 Amazon cities plus 14 from the northeast region, where prevalence was increasing rapidly. Prevalence levels were lower in the south and centre-west, and intermediate in the southeast, where the highest level was found in Rio de Janeiro (7·5% [4·2-12·2]). In the second survey, prevalence was similar in men and women, but an increased prevalence was observed in participants aged 20-59 years and those living in crowded conditions (4·4% [3·5-5·6] for those living with households with six or more people). Prevalence among Indigenous people was 6·4% (4·1-9·4) compared with 1·4% (1·2-1·7) among White people. Prevalence in the poorest socioeconomic quintile was 3·7% (3·2-4·3) compared with 1·7% (1·4-2·2) in the wealthiest quintile. INTERPRETATION:Antibody prevalence was highly heterogeneous by country region, with rapid initial escalation in Brazil's north and northeast. Prevalence is strongly associated with Indigenous ancestry and low socioeconomic status. These population subgroups are unlikely to be protected if the policy response to the pandemic by the national government continues to downplay scientific evidence. FUNDING:Brazilian Ministry of Health, Instituto Serrapilheira, Brazilian Collective Health Association, and the JBS Fazer o Bem Faz Bem.

Project description:BackgroundPrevalence estimates from surveys with low response rates are prone to non-response bias if respondents and non-respondents differ on the outcome of interest. This study assessed the external validity of prevalence estimates of selected maternity indicators from four national maternity surveys in England which had similar survey methodology but different response rates.MethodsA secondary analysis was conducted using data from the national maternity surveys in 2006 (response rate = 63%), 2010 (response rate = 54%), 2014 (response rate = 47%) and 2018 (response rate = 29%). Unweighted and (for the 2014 and 2018 surveys) weighted survey prevalence estimates (with 95%CIs) of caesarean section, preterm birth, low birthweight and breastfeeding initiation were validated against population-based estimates from routine data.ResultsThe external validity of the survey estimates varied across surveys and by indicator. For caesarean section, the 95%CIs for the unweighted survey estimates included the population-based estimates for all surveys. For preterm birth and low birthweight, the 95%CIs for the unweighted survey estimates did not include the population-based estimates for the 2006 and 2010 surveys (or the 2014 survey for preterm birth). For breastfeeding initiation, the 95%CIs for the unweighted survey estimates did not include the population-based estimates for any survey. For all indicators, the effect of weighting (on the 2014 and 2018 survey estimates) was mostly a shift towards the population-based estimates, yet the 95%CIs for the weighted survey estimates of breastfeeding initiation did not include the population-based estimates.ConclusionThere were no clear differences in the external validity of prevalence estimates according to survey response rate suggesting that prevalence estimates may still be valid even when survey response rates are low. The survey estimates tended to become closer to the population-based estimates when weights were applied, yet the effect was insufficient for breastfeeding initiation estimates.

Dataset Information

Reliability of Nationwide Prevalence Estimates of Dementia: A Critical Appraisal Based on Brazilian Surveys.

Background

Methods and findings

Conclusions

Publications

Reliability of Nationwide Prevalence Estimates of Dementia: A Critical Appraisal Based on Brazilian Surveys.

Similar Datasets

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