Article

Odds ratio or relative risk for cross-sectional data?

International Journal of Epidemiology (Impact Factor: 6.98). 03/1994; 23(1):201-3.
Source: PubMed
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    ABSTRACT: Background: Syphilis prevalence continues to be high among at-risk populations such as men who have sex with men (MSM). In low and middle-income countries, syphilis remains a neglected epidemic with a lack of effective prevention strategies. Methods: PICASSO is a clinic-based study of MSM in Lima, Peru that includes behavioral surveys and syphilis testing with rapid plasma reagin (RPR) titers (BD Macro-Vue RPR, Becton-Dickinson, NJ) and Treponema pallidum Particle Agglutination (Serodia TP-PA, Fujirebio Inc, Japan). Participants with recent syphilis infection (RPR titer ≥1:16) were compared to participants with non-reactive titers. Participants with RPR titers 1:1-1:8 were excluded. Age in years was analyzed as a continuous variable. HIV perceived risk was self-reported on a 4-point scale. Factors associated with recent syphilis were explored using Poisson regression to compute risk ratios (RR). Results: The frequency of recent syphilis infection was 26/171 (15.2%). More individuals with recent syphilis infection were HIV-infected; 6/26 (23.0%) compared to 18/91 (19.8%) participants with nonreactive RPR titers (RR 1.16, p = 0.711). Recent syphilis infection was associated with younger age (RR 0.95, p =0.016) and higher self-perceived risk of HIV (RR 1.33, p =0.06). Insertive anal sex was associated with a lower relative risk of recent syphilis infection (RR 0.25, p = 0.05) compared to receptive or versatile. Other sexual behaviors, substance use and alcohol use were not associated with recent syphilis infection. Conclusions: Recent syphilis infection was common in the clinic-based sample of high-risk MSM. Frequent syphilis and HIV co-infection suggest an integrated strategy is necessary for prevention and treatment efforts. Our findings suggest that patterns of syphilis transmission are only partially explained by current measures of behavioral risk.
    National STD Prevention Conference 2014 Centers for Disease Control and Prevention; 06/2014
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    ABSTRACT: The objective for this paper was to present and discuss the use of odds ratios and prevalence ratios using real data with a complex sampling design. We carried out a cross-sectional study using data obtained from a two-stage stratified cluster sample from a study conducted in 2001-2002 (n = 1,958). Odds ratios and prevalence ratios were obtained by unconditional logistic regression and Poisson regression, respectively, for later comparison using the Stata statistical package (v. 7.0). Confidence intervals and design effects were considered in the evaluation of the precision of estimates. Two outcomes of a cross-sectional study with different prevalences were evaluated: vaccination against influenza (66.1%) and self-referred lung disease (6.9%). In the high-prevalence scenario, using prevalence ratios the estimates were more conservative and we found narrower confidence intervals. In the low-prevalence scenario, we found no important numeric differences between the estimates and standard errors obtained using the two techniques. A design effect greater than one indicates that the sample design has increased the variance of the estimate. However, it is the researcher's task to choose which technique and measure to use for each data set, since this choice must remain within the scope of epidemiology.
    Revista Brasileira de Epidemiologia 09/2008; 11(3):347-355.
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    ABSTRACT: Purpose: The aim of the study was to determine the relationship between orofacial pain (OFP) in the community and other symptoms. Materials and Methods: This cross-sectional population-based study was conducted in a general medical practice in South East Cheshire, UK. Questionnaires were mailed to a random sample of 4,000 adults aged 18-65 years, of whom 2,504 responded (adjusted participation rate 74%). Results: The current study showed an association between self-reported OFP and all the other symptoms measured. The strongest association was found for a high level of sleep disturbance (relative risk (RR) 3.7; 95% Confidence Interval (CI) 2.9-4.9), tenderness of jaw muscles in the morning (RR 3.7; 95% CI 3.3-4.1), persons with frequent headaches (RR 3.1; 95% CI 2.7-3.5), and tiredness or stiffness of jaw muscles (RR 2.6; 95% CI 2.3-3.0). Having pain in the body other than the head was associated with a relative risk of OFP of 1.6 (95% CI 1.4-1.9), and increased risk persisted when individual body locations were considered (back, abdominal, forearm, shoulder and knee pain). Those who took medication for bowels had a higher risk of OFP (RR 1.4; 95% CI 1.1-1.8). Problems with micturition were associated with an elevated risk of 1.5 (95% CI 1.0-2.0). None of these results changed significantly after adjustment for age and gender. Conclusions: This cross-sectional community-based study contributes additional information on the relationship between other symptoms and OFP. It suggests that future research should adopt a multidisciplinary approach to OFP, however further longitudinal studies are required establishing the association between other symptoms and the onset of OFP.

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