Background: In clinical setting, to answer a research question, very often more than one outcome variables are used which are statistically correlated. Univariate analysis approach, which is commonly used in such context, violates the assumption of independence for correlated variables, while multivariate approach could give more robust and precise clinical decision by accounting this correlation. This paper is a demonstration of the change in statistical decision in multivariate approach compared to univariate approach in analysing medical data with multiple correlated outcome variables. Method: ology: The data used in this paper was the ACCORD trial data and the variables were Systolic blood pressure (SBP) and Diastolic blood pressure (DBP) which are correlated. The condition of bivariate normality was checked after removing the outliers. We compared the differences in means of SBP and DBP separately between the groups at different follow up time points by univariate approach using unpaired 't' test and thereafter together by bivariate approach using Hotelling 'T 2' . Further the role of varied levels of correlation between SBP and DBP coupled with the variations in sample size in changing the statistical inference has been investigated. Robustness of these results were demonstrated through 1000 samples of simulated data from Accord trial data. Results: The statistical decision regarding difference in means of either SBP or DBP between the two groups at baseline, 12th, 36th and 84th month in both univariate and bivariate approaches were similar. At baseline and 84th month the hypotheses were accepted and at 12th and 36th month the hypotheses were rejected with both the approaches. However at 60th and 72nd month the univariate and multivariate approach results contradicted each other which reflect the significance of correlation in modifying the inference. The analysis results further indicated that varied levels of correlation and sample size too modify the inference in bivariate approach and contradict univariate results. Conclusion: Studies with multiple correlated outcomes, the multivariate approach which accounts this statistical correlation has potential to change statistical decisions and provide more precise results. Hence multivariate approach is recommended in such situations.
Background: Sample size estimation is one of the key components in the initial stage of any health research. The validity of an observational study in estimating prevalence of an outcome of interest is primarily determined by the precision of the estimate. This is generally motivated by the method of sample size estimation. The choice of incorporating absolute precision or relative precision in estimating the sample size of proportions has been a grey area for many years. The objectives of the study were to investigate the role of relative and absolute precision in sample size estimation of proportion and also to provide an easy guide for estimation of sample size using relative and absolute precision using real life examples. Materials and Methods: Sample sizes for different proportions using varying levels of relative and absolute precision were estimated and the variations in the sample size using both methods were graphically plotted. Results: Sample size decreases exponentially with increase in anticipated prevalence in the case of relative precision whereas for absolute precision, it follows a bell-shaped curve. Conclusions: The current study provides scenarios where and how absolute and relative precision can be used. Also, the relation between absolute and relative precision is provided. Key words: sample size, prevalence, health research, relative precision, absolute precision
Introduction: Treatment of nephrotic syndrome with corticosteroid can cause several side- effects including behavioral abnormalities. The objectives of the study were to observe the proportion of non-relapsers having persistence of behavioral abnormalities after completion of treatment of initial episode and compare the abnormalities with relapsers, and to determine risk factors for persistence. Methods: Seventy-five children with a first episode of idiopathic nephrotic syndrome and 60 normal children were rated by parents for behavioral problems using the Child Behavior Checklist. The Parenting Stress Index was also evaluated. The children were rated before treatment and 12 and 36 weeks after. Results: Both relapsers and non-relapsers showed abnormalities in internalizing and externalizing domains at 12 weeks of steroid therapy. Non-relapsers had abnormal scores in the internalizing domain in 63.5 % and externalizing domain in 48.1% of cases at 36 weeks. Relapsers had abnormal scores in all the three behavior domains, but a significantly higher proportion of relapsers had abnormal scores regarding total behavior (65.2% vs 28.8%, p<0.01) and child domains (100% vs 57.7%, p<0.001) of Parenting Stress Index in comparison to non-relapsers at 36 weeks. Occurrence of relapse increased the risk (odds ratio 5.76, 95% CI 1.35-10.76, p< 0.001) for persistence of abnormal total behavior at 36 weeks follow-up. Conclusion: Persistence of abnormalities was observed not only in relapsers but also in non-relapsers. Relapse was found to be a significant risk factor for persistence of abnormal behaviors in these patients.
Background: Still many Indian states observe low spaced births and high fertility above replacement level; mostly contributed by disadvantaged society. Factors influencing are entrenched in ignorance, male child desire and traditional culture to some extent. Aim and Objectives: To determine knowledge and practice of spacing methods of contraception and the associated socio-demographic variables. Settings and Design: Cross-sectional study Methods and Material: A community based cross-sectional study; conducted among 590 eligible couples of slum community of Varanasi selected following two stage stratified random sampling. First stage stratification was based on slum size and second stage was caste class group size. . Statistical analysis used: Knowledge and practice were described in percent and the associated factors were identified by logistic regression. Statistical significance was judged at ? = 0.05. Results: Overall knowledge of any spacing methods was in only 61.2% women and practice ever in married life was 44.4%, even those who knew the methods ever practice was only 66.2%. Knowledge gained was mostly through husband for condom, health professional for Cu-T and oral pills. In recent years (last 7 years), overall practice of spacing methods was only 30%. Contraception practice was association survival of child (lesser, if child surviving), number of births (higher, if more living born), religion (lesser, if Muslim), type of house (lesser, if living in hut/kachcha houses) and wife educational attainment (lesser, if low education level) Conclusion: Eligible couples of slum community need knowledge of contraception as well as motivation to practice spacing methods to reduce higher level of fertility. Keywords: Contraception, spacing methods, fertility
RESUMO Introdução: A síndrome nefrótica idiopática córtico-resistente (SNICR) apresenta desfechos variáveis em crianças. O objetivo principal deste estudo foi avaliar a taxa de remissão cumulativa. Os objetivos secundários foram avaliar fatores que afetam status de remissão, sobrevida da função renal e efeitos adversos de medicamentos. Métodos: Foram incluídos 114 pacientes com SNCR. Utilizou-se protocolo de tratamento baseado em inibidores de calcineurina juntamente com prednisolona e inibidor da enzima conversora de angiotensina. Os pacientes foram acompanhados durante 5 anos. Resultados: A idade mediana foi 4,5 anos; 53,5% dos casos tinham entre 1 e 5 anos. 62 pacientes (54,4%) estavam em estágio inicial; 52 (45,6%) em estágio tardio da SNCR. A TFGecr mediana foi 83,5 mL/min/1,73 m2 na apresentação. Dos 110 pacientes, 63 (57,3%) alcançaram remissão [remissão completa 30 (27,3%), remissão parcial 33 (30%)], e 47 (42,7%) não apresentaram remissão. A sobrevida da função renal foi 87,3%; 14 casos (12,7%) progrediram para DRC (G3-8, G4-3, G5-1, G5D-2). A duração mediana do acompanhamento foi 36 meses (IIQ 24, 60). Idade no início, ciclosporina/tacrolimus, TFGecr e histopatologia (DLM/GESF) não afetaram a remissão. Igualmente, status de remissão, além da idade no início, protocolo de medicamentos e histopatologia não afetaram significativamente a função renal por 5 anos. Observou-se hipertensão, fácies cushingoide, baixa estatura, catarata e obesidade em 37,7; 29,8; 25,5; 17,5; e 0,7% dos casos, respectivamente. Conclusão: Aproximadamente metade dos casos alcançou remissão. Idade no início, uso de ciclosporina/tacrolimus e lesão histopatológica não afetaram o status de remissão nem a sobrevida da função renal a curto prazo na SNICR.
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