Population-based Health Survey Research Articles

Somatic symptom profiles in the general population: a latent class analysis in a Danish population-based health survey.

PurposeThe aim of this study was to identify and describe somatic symptom profiles in the general adult population in order to enable further epidemiological research within multiple somatic symptoms.MethodsInformation on 19 self-reported common somatic symptoms was achieved from a population-based questionnaire survey of 36,163 randomly selected adults in the Capital Region of Denmark (55.4% women). The participants stated whether they had been considerably bothered by each symptom within 14 days prior to answering the questionnaire. We used latent class analysis to identify the somatic symptom profiles. The profiles were further described by their association with age, sex, chronic disease, and self-perceived health.ResultsWe identified 10 different somatic symptom profiles defined by number, type, and site of the symptoms. The majority of the population (74.0%) had a profile characterized by no considerable bothering symptoms, while a minor group of 3.9% had profiles defined by a high risk of multiple somatic symptoms. The remaining profiles were more likely to be characterized by a few specific symptoms. The profiles could further be described by their associations with age, sex, chronic disease, and self-perceived health.ConclusionThe identified somatic symptom profiles could be distinguished by number, type, and site of the symptoms. The profiles have the potential to be used in further epidemiological studies on risk factors and prognosis of somatic symptoms but should be confirmed in other population-based studies with specific focus on symptom burden.

Body height and mortality - mortality follow-up of four Swiss surveys.

Adult body height is largely determined by genetics, but also by dietary factors, which in turn depend on socioeconomic status and lifestyle. We examined the association between adult body height and mortality in Switzerland, a country with three main language regions with different cultural background. We included 16,831 men and 18,654 women, who participated in Swiss population-based health surveys conducted 1977-1993 and who were followed up until end of 2008. Multivariable Cox proportional hazards models were computed to examine the association of body height with overall, cardiovascular, and cancer mortality. We observed a positive association between adult body height and all-cause mortality in women (HR=1.34, 95% CI 1.10-1.62, tallest vs. average women). In men, mortality risk decreased with increasing height, with shortest men tending to have higher (1.06, 0.94-1.19) and tallest men a lower (0.94, 0.77-1.14) risk compared with men of average height (p-trend 0.0001). Body height was associated with cancer mortality in women, such that tallest women had a higher risk of dying from cancer than women of average height (1.37, 1.02-1.84), but there was no such association in men (0.95, 0.69-1.30). In both sexes, height was not associated with cardiovascular mortality in a statistically significant manner. Our study does not support an inverse association of body height with all-cause mortality. On the contrary, our data suggests a higher overall risk in taller women, mainly driven by a positive association between body height and cancer mortality.

Absolute values of lung function explain the sex difference in breathlessness in the general population

Activity-related breathlessness is twice as common among females as males in the general population and is associated with adverse health outcomes. We tested whether this sex difference is explained by the lower absolute forced expiratory volume in 1 s (FEV1) or forced vital capacity (FVC) in females.This was a cross-sectional analysis of 3250 subjects (51% female) aged 38-67 years across 13 countries in the population-based third European Community Respiratory Health Survey. Activity-related breathlessness was measured using the modified Medical Research Council (mMRC) scale. Associations with mMRC were analysed using ordered logistic regression clustering on centre, adjusting for post-bronchodilator spirometry, body mass index, pack-years smoking, cardiopulmonary diseases, depression and level of exercise.Activity-related breathlessness (mMRC ≥1) was twice as common in females (27%) as in males (14%) (odds ratio (OR) 2.21, 95% CI 1.79-2.72). The sex difference was not reduced when controlling for FEV1 % predicted (OR 2.33), but disappeared when controlling for absolute FEV1 (OR 0.89, 95% CI 0.69-1.14). Absolute FEV1 explained 98-100% of the sex difference adjusting for confounders. The effect was similar within males and females, when using FVC instead of FEV1 and in healthy never-smokers.The markedly more severe activity-related breathlessness among females in the general population is explained by their smaller spirometric lung volumes.

Smoking, alcohol and drug use in youth and adults with attention-deficit hyperactivity disorder.

BackgroundPrevious research suggests a relationship between attention-deficit hyperactivity disorder (ADHD) and smoking, alcohol and illicit drug use, however most studies have focused on adolescents or young adults, or clinically ascertained samples.AimsTo analyse population-based data on the relationship between ADHD and at-risk health behaviours in adolescents and adults.MethodData were derived from a Statistics Canada population-based health survey. The association between the diagnosis of ADHD and smoking, alcohol use, and illicit drug use was examined.ResultsIndividuals with ADHD started smoking at a younger age. They consumed more alcoholic drinks on drinking days, and women with ADHD were more likely to engage in binge drinking. Women over the age of 25 and men with ADHD were more likely to meet alcohol-dependence lifetime criteria. People with ADHD were at a greater risk of drug misuse and dependence.ConclusionsPeople with ADHD are more likely to partake in at-risk behaviours.Declaration of interestNone.Copyright and usage© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

Increasing research capacity with ICES Data & Analytic Services (DAS)

ABSTRACTBackgroundThe Institute for Clinical Evaluative Sciences (ICES) is a not-for-profit organization that conducts research to evaluate health care delivery and outcomes. Established in 1992, ICES houses a vast and secure array of linkable, coded health-related data on more than 13 million Ontarians, including health services data, health care provider data, registries and population-based health surveys. ICES has a reputation for generating strong evidence-based knowledge to inform policy and practice, however the use of the data was restricted to ICES’ purposes. In March 2014, ICES launched the Data & Analytic Services (DAS) platform with the primary objective of increasing access to its data to publicly-funded researchers, health care providers and administrators, policymakers and students.
 MethodDAS provides access to highly de-identified, risk-reduced datasets created from ICES’ data holdings; analytic support; and complete data analysis and report writing services. DAS also enables the importation of external data for linkage to ICES’ data holdings. Research objectives and methodology are led by the requestor and ICES analysts rely on their subject matter expertise to direct the deliverables.
 ResultsSince launch, over 200 requests from Canada, United States and United Kingdom have been adjudicated, of which 187 have been deemed feasible and eligible. Over the same period of time, ICES as an organization had over 700 active projects of which 348 were initiated, an increase in capacity of 26%. Though Toronto-based researchers represent the majority of the requests (62%), there have been requests from outside Ontario interested in comparing aspects of Ontario’s healthcare to their home province. Research topics have varied and include assessments of health care provision by sector, disease prevalence and treatment, and statistical methods. An unexpected outcome of increasing access has been the large interest from small physician groups and knowledge users who are not typically involved in research for academic purposes. Access to ICES’ data holdings provides an opportunity to examine a larger cohort of patients who share the same characteristics as their clinic patients or group. Furthermore, by enabling remote access to the data, DAS is able to leverage the capabilities of ICES’ data holdings and increase research capacity in a short period of time.
 ConclusionIn making one of the most comprehensively linked health administrative data repositories in the world widely available to the broader research and healthcare community, DAS engages investigators involved in front-line care, stimulates new avenues of research and fosters collaboration that was previously unachievable.

Menopause Is Associated with Accelerated Lung Function Decline.

Menopause is associated with changes in sex hormones, which affect immunity, inflammation, and osteoporosis and may impair lung function. Lung function decline has not previously been investigated in relation to menopause. To study whether lung function decline, assessed by FVC and FEV1, is accelerated in women who undergo menopause. The population-based longitudinal European Community Respiratory Health Survey provided serum samples, spirometry, and questionnaire data about respiratory and reproductive health from three study waves (n = 1,438). We measured follicle-stimulating hormone and luteinizing hormone and added information on menstrual patterns to determine menopausal status using latent class analysis. Associations with lung function decline were investigated using linear mixed effects models, adjusting for age, height, weight, pack-years, current smoking, age at completed full-time education, spirometer, and including study center as random effect. Menopausal status was associated with accelerated lung function decline. The adjusted mean FVC decline was increased by -10.2 ml/yr (95% confidence interval [CI], -13.1 to -7.2) in transitional women and -12.5 ml/yr (95% CI, -16.2 to -8.9) in post-menopausal women, compared with women menstruating regularly. The adjusted mean FEV1 decline increased by -3.8 ml/yr (95% CI, -6.3 to -2.9) in transitional women and -5.2 ml/yr (95% CI, -8.3 to -2.0) in post-menopausal women. Lung function declined more rapidly among transitional and post-menopausal women, in particular for FVC, beyond the expected age change. Clinicians should be aware that respiratory health often deteriorates during reproductive aging.

Multinational Population-Based Health Surveys Linked to Outcome Data: An Untapped Resource

ABSTRACTObjectivesIncreasingly, national health surveys are being linked to vital statistics and health care information, providing a new and unique source of individual population health data. Given that nationally-representative health surveys are performed in over a hundred countries, these linkages create comprehensive data sets that are potentially larger than most existing cohort studies. To date, this resource has not been utilized.
 ApproachThe purpose, study base, content and methods of the Canadian Community Health Survey (CCHS) cycles 2.1 (2003-04) and 3.1 (2005-06) and the United States 2000 and 2005 National Health Interview Survey (NHIS) were examined for comparability and consistency. Smoking, alcohol, physical activity and diet questions were identified, question construct and response categorization were compared, and variable constructions possible for both national health surveys were created. All respondents 20+ years of age were identified and stratified by country and sex. Cox proportional hazard models were used to estimate 5-year hazards of mortality associated with the common smoking, alcohol, physical activity and diet variables.
 ResultsThe CCHS and NHIS are highly consistent and comparable. Health behaviour questions are similar and permit the creation of smoking, alcohol, physical activity and diet variables that are comparable across surveys. A total of 284 475 survey respondents from Canada and the United States (CCHS, N= 226 731; NHIS, N= 57 744) were included. The largest mortality hazards were associated with female heavy smokers in both Canada (HR: 2.91; 95% CI: 2.52, 3.37) and the United States (Female HR: 2.96; 95% CI: 2.59, 3.38), compared to non-smokers. Moderate variation in the age adjusted all-cause mortality hazard ratios was observed; both smoking and physical activity hazard ratios were consistently higher in the United States than in Canada.
 ConclusionThis study provides initial support for the methodological feasibility of pooling linked population health surveys however, challenges introduced by dissimilarities will require the use of innovative methodologies, and discussions regarding how to manage jurisdictional data restrictions and privacy issues are needed. Pooled population health data has the potential to improve national and international health surveillance and public health.

Collective violence and the health of the elderly: a cross-sectional analysis of a population-based national survey in Mexico.

ABSTRACTObjective.To describe the association between collective violence and the health of older adults in Mexico.Methods.The data analyzed were taken from a Mexican population-based national survey of health and nutrition that included a representative sample of adults over 60 years of age and from an index of violence for each of the states of Mexico that was compiled by a major research center. Five of the most common geriatric ailments (weight loss, depressive symptoms, falls, positive affectivity, and disability) were crossed with the violence index score assigned to each state.Results.A total of 7 108 older adults were included in the analysis. Among the five geriatric health problems, weight loss had the strongest association with violence, even when an adjusted model was used. For weight loss, that association increased as the level of collective violence rose. With the adjusted model, there was also an association of severe collective violence with disability and with low positive affectivity.Conclusions.Our results show that there is an association of collective violence with weight loss and other geriatric problems. Collective violence could indirectly affect individuals’ health, especially older persons and other vulnerable groups.

Comparison of response patterns in different survey designs: a longitudinal panel with mixed-mode and online-only design

BackgroundIncreasing availability of the Internet allows using only online data collection for more epidemiological studies. We compare response patterns in a population-based health survey using two survey designs: mixed-mode (choice between paper-and-pencil and online questionnaires) and online-only design (without choice).MethodsWe used data from a longitudinal panel, the Hygiene and Behaviour Infectious Diseases Study (HaBIDS), conducted in 2014/2015 in four regions in Lower Saxony, Germany. Individuals were recruited using address-based probability sampling. In two regions, individuals could choose between paper-and-pencil and online questionnaires. In the other two regions, individuals were offered online-only participation. We compared sociodemographic characteristics of respondents who filled in all panel questionnaires between the mixed-mode group (n = 1110) and the online-only group (n = 482). Using 134 items, we performed multinomial logistic regression to compare responses between survey designs in terms of type (missing, “do not know” or valid response) and ordinal regression to compare responses in terms of content. We applied the false discovery rates (FDR) to control for multiple testing and investigated effects of adjusting for sociodemographic characteristic. For validation of the differential response patterns between mixed-mode and online-only, we compared the response patterns between paper and online mode among the respondents in the mixed-mode group in one region (n = 786).ResultsRespondents in the online-only group were older than those in the mixed-mode group, but both groups did not differ regarding sex or education. Type of response did not differ between the online-only and the mixed-mode group. Survey design was associated with different content of response in 18 of the 134 investigated items; which decreased to 11 after adjusting for sociodemographic variables. In the validation within the mixed-mode, only two of those were among the 11 significantly different items. The probability of observing by chance the same two or more significant differences in this setting was 22%.ConclusionsWe found similar response patterns in both survey designs with only few items being answered differently, likely attributable to chance. Our study supports the equivalence of the compared survey designs and suggests that, in the studied setting, using online-only design does not cause strong distortion of the results.

Cigarette smoking and the risk of primary Sj\xf6gren\u2019s syndrome: a nested case control study

BackgroundSmoking is reported to affect the risk of a number of chronic disorders, including rheumatic diseases. Previous cross-sectional studies have shown a lower frequency of smoking in patients with primary Sjögren’s syndrome (pSS). The aim of this study was to investigate the impact of smoking and socioeconomic status on the risk of subsequent diagnosis of pSS in a nested case-control study.MethodParticipants in two large population-based health surveys who were later diagnosed with pSS were identified through linkage with the Malmö Sjögren’s Syndrome Register. Matched controls were obtained from the health surveys.ResultsSixty-three patients with pSS with pre-diagnostic data from the health surveys were identified. Current smoking was associated with a significantly lower risk of later being diagnosed with pSS (odds ratio (OR) 0.3; 95% CI 0.1–0.6). Furthermore, former smoking was associated with an increased risk of subsequent pSS diagnosis (OR 4.0; 95% CI 1.8–8.8) compared to never smoking. Similar results were found in a sub-analysis of patients with reported symptom onset after inclusion in the health surveys. Socioeconomic status and levels of formal education had no significant impact on the risk of later being diagnosed with pSS.ConclusionIn this nested case-control study, current smoking was associated with a reduced risk of subsequent diagnosis of pSS. In addition, former smoking was associated with an increased risk. Whether this reflects a biological effect of cigarette smoking or other mechanisms should be further investigated in future studies.

Mental health problems among survivors in hard-hit areas of the 5.12 Wenchuan and 4.20 Lushan earthquakes

Background: Earthquake exposure has often been associated with psychological distress. However, little is known about the cumulative effect of exposure to two earthquakes on psychological distress and in particular, the effect on the development of post-traumatic stress disorder (PTSD), anxiety and depression disorders.Aims: This study explored the effect of exposure on mental health outcomes after a first earthquake and again after a second earthquake.Methods: A population-based mental health survey using self-report questionnaires was conducted on 278 people in the hard-hit areas of Lushan and Baoxing Counties 13-16 months after the Wenchuan earthquake (Sample 1). 191 of these respondents were evaluated again 8-9 months after the Lushan earthquake (Sample 2), which struck almost 5 years after the Wenchuan earthquake.Results: In Sample 1, the prevalence rates for PTSD, anxiety and depression disorders were 44.53, 54.25 and 51.82%, respectively, and in Sample 2 the corresponding rates were 27.27, 38.63 and 36.93%. Females, the middle-aged, those of Tibetan nationality, and people who reported fear during the earthquake were at an increased risk of experiencing post-traumatic symptoms.Conclusions: Although the incidence of PTSD, anxiety and depression disorders decreased from Sample 1 to Sample 2, the cumulative effect of exposure to two earthquakes on mental health problems was serious in the hard-hit areas. Therefore, it is important that psychological counseling be provided for earthquake victims, and especially those exposed to multiple earthquakes.

Immigration policies and mental health morbidity among Latinos: A state-level analysis

RationaleDespite abundant state-level policy activity in the U.S. related to immigration, no research has examined the mental health impact of the overall policy climate for Latinos, taking into account both inclusionary and exclusionary legislation. ObjectiveTo examine associations between the state-level policy climate related to immigration and mental health outcomes among Latinos. MethodsWe created a multi-sectoral policy climate index that included 14 policies in four domains (immigration, race/ethnicity, language, and agricultural worker protections). We then examined the relation of this policy climate index to two mental health outcomes (days of poor mental health and psychological distress) among Latinos from 31 states in the 2012 Behavioral Risk Factor Surveillance System (BRFSS), a population-based health survey of non-institutionalized individuals aged 18 years or older. ResultsIndividuals in states with a more exclusionary immigration policy climate had higher rates of poor mental health days than participants in states with a less exclusionary policy climate (RR: 1.05, 95% CI: 1.00, 1.10). The association between state policies and the rate of poor mental health days was significantly higher among Latinos versus non-Latinos (RR for interaction term: 1.03, 95% CI: 1.01, 1.06). Furthermore, Latinos in states with a more exclusionary policy climate had 1.14 (95% CI: 1.04, 1.25) times the rate of poor mental health days than Latinos in states with a less exclusionary policy climate. Results were robust to individual- and state-level confounders. Sensitivity analyses indicated that results were specific to immigration policies, and not indicators of state political climate or of residential segregation. No relationship was observed between the immigration policy index and psychological distress. ConclusionThese results suggest that restrictive immigration policies may be detrimental to the mental health of Latinos in the United States.

Utilization of Medical Rehabilitation Services in Germany: A Comparative Analysis of Survey and Routine Data

Population ageing leads to an increase in age-related diseases. Consequently, the need for medical rehabilitation services is also rising. Rehabilitation service in Germany is offered by several rehabilitation carriers. There is no homogeneous rehabilitation statistics, resulting in insufficient data. This paper analyses utilization of medical rehabilitation services in Germany. It uses data from a representative population-based health survey. The results were extrapolated to the general population in Germany and compared with routine data. Survey data used were those of the German Health Interview and Examination Survey for Adults (DEGS1) with 7 988 participants. Utilization rates were extrapolated to the general population. Routine data sources are the diagnostic data of the Federal Statistical Office on patients using prevention or rehabilitation facilities. Further data sources are the published statistics of the rehabilitation carriers. In order to compute the total number of rehabilitation cases, where data were lacking in the statistics of the rehabilitation carriers, an estimate was made. The analysis of the different data sources shows similar results. In 2010, there were approximately 2.2 million rehabilitation cases in Germany. Around 10% of rehabilitation measures were carried out in the ambulatory setting. Analyses of structural characteristics in the routine data are possible but not recommendable because of bias in the data. Without detailed data on age structure and trends, challenges of demographic changes and changes in the illness spectrum cannot be adequately described. Because of a lack of sufficient diagnosis-based data, statements on the appropriateness of medical rehabilitation services offered by rehabilitation carriers cannot be made.

Physical activity and incident asthma in adults: the HUNT Study, Norway

ObjectiveWe aimed to investigate the associations of physical activity and change in physical activity with incident asthma in a cohort of Norwegian adults.DesignWe conducted a prospective cohort study using data...

Psychosocial factors are strongly associated with insomnia in users and nonusers of prescribed sleep medication: evidence from the HUNT3 study.

ObjectiveThe aim of this study was to examine how neuroticism, stressful life events, self-rated health, life satisfaction, and selected lifestyle factors were related to insomnia both by sex and among users and nonusers of prescribed sleep medication (PSM).DesignCross-sectional data from the Norwegian Nord-Trøndelag Health Study (HUNT3, 2006–2008), a population-based health survey, were linked to individual data from the Norwegian Prescription Database.MethodsLogistic regression analyses were used to investigate the associations between the selected variables and insomnia in both males and females and among subjects using and not using PSM. Individuals were considered to have a presumptive diagnosis of insomnia disorder if they reported difficulty with sleep initiation, sleep maintenance, or early morning awakening several days per week for the last 3 months. PSMs were categorized as anxiolytics or hypnotics; the dose was estimated according to defined daily dose (DDD).ResultsOf the total 50,805 participants, 6,701 (13.2%) used PSM. The proportions of PSM users were larger among elderly participants. Increased risk of insomnia was strongly associated with poor self-rated health and higher level of neuroticism. These associations were evident for both sexes and were similar among both users and nonusers of PSM. Low satisfaction with life was strongly related to insomnia, but only among nonusers of PSM. Increased doses of PSM were not associated with reduced likelihood of insomnia.ConclusionInsomnia is a problem among both users and nonusers of PSM and is associated with psychosocial factors. Our findings suggest that successful treatment for sleep problems should take individual variation into account, such as age, sex, personality traits, satisfaction with life, and health perception.

Adults with One or More Functional Disabilities - United States, 2011-2014.

Nearly 40 million persons in the United States have a disability, as defined by responses to six questions recommended by the U.S. Department of Health and Human Services as the national standard for identifying disabilities in population-based health surveys (1). Although these questions have been used to estimate prevalence of functional disabilities overall, as well as types of functional disabilities (disability type), no study has yet investigated the characteristics of U.S. adults by number of disability types. Knowing the characteristics of persons living with multiple disability types is important for understanding the overall functional status of these persons. CDC analyzed data from the family component of the National Health Interview Survey (NHIS) for the years 2011-2014 to estimate the percentage of adults aged 18-64 years with one, two, three, or four or more disability types, by selected demographic and socioeconomic characteristics. Overall, 22.6 million (11.9%) working-age adults were found to have any disability, and in this population, most (12.8 million) persons had only one disability type. A generally consistent pattern between increasing indicators of low socioeconomic status and the number of disability types was observed. Understanding the demographic and socioeconomic characteristics of working-age adults with disabilities, including those with multiple disability types, might help to further the inclusion of persons with disabilities in public health programs and policies.

Community vulnerability and symptoms of acute respiratory infection among preschool age children in the Democratic Republic of Congo, Malawi and Nigeria: evidence from Demographic and Health Surveys

BackgroundAs a consequence of the global spread of HIV infection in sub-Saharan Africa, the impact of the AIDS pandemic has contributed to more than 40 million orphaned and vulnerable children...

The effect of clinical features and glucocorticoids on biopsy findings in giant cell arteritis.

BackgroundTo investigate the effect of baseline clinical characteristics and glucocorticoid treatment on temporal artery biopsy (TAB) findings in patients with giant cell arteritis (GCA).MethodsIndividuals who developed GCA after inclusion in two population-based health surveys were identified through linkage to the local and the national patient registers. In addition, other patients diagnosed with GCA at the Departments of Internal Medicine and Rheumatology at an area hospital were included. A structured review of medical records and TAB pathology reports was performed. The presence or absence of giant cells, granuloma, fragmented internal elastic lamina, fibrosis and grade of inflammatory infiltrates were recorded.ResultsIn 183 cases with a confirmed clinical diagnosis of GCA, 139 were biopsied after start of glucocorticoids (median treatment duration 3 days; interquartile range 2–5). Patients with a positive TAB (77 %) had significantly higher C-reactive protein (CRP; p = 0.007) and erythrocyte sedimentation rate (ESR; p = 0.03) at the time of clinical diagnosis. A positive TAB tended to more common in women, but there was no difference in the proportion of patients with polymyalgia rheumatica or visual symptoms.Patients biopsied before or on the same day as initial treatment where more likely than those biopsied 1–3 days after treatment start to have positive biopsy [odds ratio (OR) 2.86; 95 % CI 1.06–7.70] as well as inflammatory infiltrates (OR 3.30; 95 % CI 1.15–9.49).There was no significant difference in the proportions of a fragmented internal lamina (p = 0.86), giant cells (p = 0.10), granuloma (p = 0.19), minor inflammatory infiltrates (p = 0.47), major inflammatory infiltrates (p = 0.09), or overall positive biopsy (p = 0.17) report by treatment duration comparing: ≤ 0 days, 1–3 days, 4–6 days, 7–28 days. Among those biopsied 7–28 days after start of treatment, 80 % of TABs were positive, and histopathology features were not substantially different from those biopsied after shorter glucocorticoid treatment.ConclusionBiopsies were more likely to be positive and have characteristic histopathologic features in patients with high CRP and ESR, and prior to start of corticosteroid treatment TABs taken 1–4 weeks after initiation of glucocorticoid treatment reveal changes consistent with GCA and therefore still yields clinically useful information for the diagnosis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-016-1225-2) contains supplementary material, which is available to authorized users.

Adolescent mental health and earnings inequalities in adulthood: evidence from the Young-HUNT Study

BackgroundPrevious studies have shown that adolescent mental health problems are associated with lower employment probabilities and risk of unemployment. The evidence on how earnings are affected is much weaker, and...

Comparative effectiveness of water and salt community-based fluoridation methods in preventing dental caries among schoolchildren.

To compare the effectiveness of water and salt community-based fluoridation methods on caries experience among schoolchildren. Data derived from two population-based oral health surveys of 12-year-old schoolchildren exposed to different community-based fluoridation methods were compared: artificially fluoridated water in Porto Alegre, South Brazil and artificially fluoridated salt in Montevideo, Uruguay. Data on socio-demographic characteristics, maternal education and oral hygiene were collected. Dental caries was defined according to the WHO criteria (cavitated lesions) and to the modified WHO criteria (active noncavitated lesions and cavitated ones). The association between community-based fluoridation methods and dental caries was modelled using logistic (caries prevalence) and Poisson regression (DMFT). Odds ratios (OR), rate ratios (RR), and the 95% confidence intervals (CI) were estimated. A total of 1528 in Porto Alegre and 1154 in Montevideo were examined (response rates: 83.2% and 69.6%, respectively). Adjusted estimates for caries prevalence and DMFT showed that schoolchildren from Porto Alegre were less affected by dental caries than their counterparts from Montevideo, irrespective of the criteria used. After adjusting for important characteristics, schoolchildren exposed to fluoridated salt had significantly higher likelihood of having caries (WHO criteria) than those exposed to fluoridated water (OR for prevalence=1.61, 95% CI=1.26-2.07; RR for DMFT=1.32, 95% CI=1.16-1.51). Similar differences were observed using the modified WHO criteria. Fluoridated water appears to provide a better protective effect against dental caries than fluoridated household salt among schoolchildren from developing countries.