A simple method for estimating relative risk using logistic regression

Grupo Latinoamericano de Investigaciones Epidemiológicas, Organización Latinoamericana para el Fomento de la Investigación en Salud, Bucaramanga, Colombia.
BMC Medical Research Methodology (Impact Factor: 2.27). 02/2012; 12(1):14. DOI: 10.1186/1471-2288-12-14
Source: PubMed


Odds ratios (OR) significantly overestimate associations between risk factors and common outcomes. The estimation of relative risks (RR) or prevalence ratios (PR) has represented a statistical challenge in multivariate analysis and, furthermore, some researchers do not have access to the available methods. Objective: To propose and evaluate a new method for estimating RR and PR by logistic regression.
A provisional database was designed in which events were duplicated but identified as non-events. After, a logistic regression was performed and effect measures were calculated, which were considered RR estimations. This method was compared with binomial regression, Cox regression with robust variance and ordinary logistic regression in analyses with three outcomes of different frequencies.
ORs estimated by ordinary logistic regression progressively overestimated RRs as the outcome frequency increased. RRs estimated by Cox regression and the method proposed in this article were similar to those estimated by binomial regression for every outcome. However, confidence intervals were wider with the proposed method.
This simple tool could be useful for calculating the effect of risk factors and the impact of health interventions in developing countries when other statistical strategies are not available.

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Available from: Fredi Diaz-Quijano, Dec 13, 2013
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    • "New insights into inflammation in atherosclerosis have practical clinical applications in risk stratification.18)19)20) Pentraxin 3 (PTX3) was initially described as an early marker for primary local activation of innate immunity and inflammatory response.21)22)23) Because PTX3 release is likely to be a specific response to vascular damage, PTX3 levels may provide more explicit information on development and progression of atherosclerosis than nonspecific markers like C-reactive protein.24)25)26)27) "
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    ABSTRACT: Background and Objectives The aim of this study was to examine the hypothesis that pentraxin 3 (PTX3) can have a diagnostic value for predicting anatomical complexity of coronary artery stenosis as measured by the Synergy between PCI with Taxus and Cardiac Surgery (SYNTAX) score. Subjects and Methods We investigated the association of systemic arterial PTX3 with SYNTAX score among 500 patients with ischemic heart disease assigned to medical treatment (251), percutaneous coronary intervention (PCI) (197), or coronary artery bypass graft (CABG) (52). Results The clinical judgment of the cardiologists was near-perfectly concordant with the SYNTAX score. Mean {99% confidence intervals (CIs)} SYNTAX scores were 5.8 (5.1-6.6), 18.4 (17.1-19.8), and 33.2 (32.8-33.6) in patients assigned to medical therapy, PCI, and CABG, respectively. The AROC (95% CIs) for discriminating between patients with and without a high SYNTAX score (>23) was 0.920 (0.895-0.946) for systemic arterial levels of PTX3. As the systemic arterial level of PTX3 increased, the SYNTAX scores also increased almost in a curvilinear fashion, with the value corresponding to the SYNTAX score of 23 being 0.29 ng · dL-1. This cutpoint achieved a sensitivity of 0.66 (0.57-0.74), a specificity of 0.94 (0.91-0.96), a positive predictive value of 0.79 (0.70-0.87), and a negative predictive value of 0.89 (0.85-0.92). Conclusion We observed that systemic arterial levels of PTX3 were associated with the SYNTAX score in a curvilinear fashion. The discriminatory power of systemic arterial levels of PTX3 for a high SYNTAX score was excellent. The interesting finding of this study was the near perfect concordance between the decisions made by the cardiologists based on their clinical judgment and the SYNTAX score. The systemic arterial PTX3 level of 0.29 ng · dL-1 was highly specific for diagnosing complex coronary artery stenosis.
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    • "The LR on the modified dataset will be mathematically equivalent to log binomial model but uses the logit link instead of log therefore it ensures that prediction be between 0 and 1. Also, this method directly provides RR instead of OR and avoids the convergence problem of log binomial model [5]. This form of analysis over represents the total cases. "
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    • "The research team also calculated the adjusted relative risks for those determinants of incident multimorbidity, information on which was collected progressively [33]. The method of generalized linear regression with a log link, normal distribution, and robust variance estimator was used for adjusted relative risk estimation [34]. "
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    ABSTRACT: Multimorbidity, presence of two or more health conditions, is a widespread phenomenon affecting populations' health all over the world. It becomes a serious public health concern due to its negative consequences on quality of life, mortality, and cost of healthcare services utilization. Studies exploring determinants of multimorbidity are limited, particularly those looking at vulnerable populations prospectively over time. This study aimed at identifying short and long term socioeconomic, psychosocial, and health behavioral determinants of incident multimorbidity among a cohort of the 1988 Armenian earthquake survivors. The study included a representative subsample of 725 from a larger initial cohort of the earthquake survivors. Data on this subsample were collected via four phases of this cohort study during the period 1990--2012. The final logistic regression analysis eliminated all those cases with baseline multimorbidity to investigate short and long term determinants of incident multimorbidity; this subsample included 600 participants. More than 75% of the studied sample had multimorbidity. Perceived low affordability of healthcare services, poor living standards during the post-earthquake decade, and lower education were independent predictors of incident multimorbidity developed during the period 1990--2012. Stressful life events and poor social support were among psychosocial determinants of incident multimorbidity. Participants' baseline BMI reported in 1990 was independently associated with incident multimorbidity. Most of the identified determinants of incident multimorbidity in our study population were markers of social inequities, indicating that inequities pose a serious threat to both individual and public health-related outcomes. Strategies targeting to decrease such inequities along with promotion of healthy lifestyle and strengthening of social networks may considerably reduce multimorbidity among population groups with similar socioeconomic and cultural profiles.
    International Journal for Equity in Health 08/2013; 12(1):68. DOI:10.1186/1475-9276-12-68 · 1.71 Impact Factor
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