Intracluster correlation coefficients for the Brazilian Multicenter Study on Preterm Birth (EMIP): methodological and practical implications

BMC Medical Research Methodology

Jose G Cecatti²  Maria H Sousa²  Patrícia M Rheder¹  Marcelo L Nomura¹  Tabata Z Dias¹  Renato Passini Jr¹  Ricardo P Tedesco¹  Samira M Haddad¹  Giuliane J Lajos¹ 

[1] Department of Obstetrics and Gynecology, School of Medical Sciences, University of Campinas, Campinas, Brazil;Center for Studies in Reproductive Health of Campinas (Cemicamp), Campinas, Brazil

关键词: Neonatal morbidity;    Indicated preterm delivery;    Premature rupture of membranes;    Spontaneous preterm labor;    Preterm birth;    Intracluster correlation coefficient;   

Others  :  866355
DOI  :  10.1186/1471-2288-14-54

 received in 2013-11-27, accepted in 2014-04-14,  发布年份 2014

【 摘 要 】

Background

Cluster-based studies in health research are increasing. An important characteristic of such studies is the presence of intracluster correlation, typically quantified by the intracluster correlation coefficient (ICC), that indicate the proportion of data variability that is explained by the way of clustering. The purpose of this manuscript was to evaluate ICC of variables studied in the Brazilian Multicenter Study on Preterm Birth.

Methods

This was a multicenter cross-sectional study on preterm births involving 20 referral hospitals in different regions of Brazil plus a nested case–control study to assess associated factors with spontaneous preterm births. Estimated prevalence rates or means, ICC with 95% confidence intervals, design effects and mean cluster sizes were presented for more than 250 maternal and newborn variables.

Results

Overall, 5296 cases were included in the study (4,150 preterm births and 1,146 term births). ICC ranged from <0.001 to 0.965, with a median of 0.028. For descriptive characteristics (socio-demographic, obstetric history and perinatal outcomes) the median ICC was 0.014, for newborn outcomes the median ICC was 0.041 and for process variables (clinical management and delivery), it was 0.102. ICC was <0.1 in 78.4% of the variables and <0.3 for approximately 95% of them. Most of ICC >0.3 was found in some clinical management aspects well defined in literature such as use of corticosteroids, indicating there was homogeneity in clusters for these variables.

Conclusions

Clusters selected for Brazilian Multicenter Study on Preterm Birth had mainly heterogeneous findings and these results can help researchers estimate the required sample size for future studies on maternal and perinatal health.

【 授权许可】

   
2014 Lajos et al.; licensee BioMed Central Ltd.

【 参考文献 】

• [1]Ukoumunne OC, Gulliford MC, Chinn S, Sterne JA, Burney PG: Methods for evaluating area-wide and organisation-based interventions in health and health care: a systematic review. Health Technol Assess 1999, 3(5):iii-92.
• [2]Kish L: Survey sampling. New York: John Wiley & Sons; 1965.
• [3]Donner A, Koval JJ: Design considerations in the estimation of the intraclass correlation. Ann Hum Genet 1982, 46:271-277.
• [4]Campbell MK, Grimshaw JM, Elbourne DR: Intracluster correlation coefficients in cluster randomised trials: empirical insights into how should they be reported. BMC Med Res Methodol 2009, 4:9.
• [5]Killip S, Mahfoud Z, Pearce K: What is an intracluster correlation coefficient? Crucial concepts for primary care researchers. Ann Fam Med 2004, 2:204-208.
• [6]Adams G, Gulliford MC, Ukoumunne OC, Eldridge S, Chinn S, Campbell MJ: Patterns of intra-cluster correlation from primary care research to inform study design and analysis. J Clin Epidemiol 2004, 57:785-794.
• [7]Hayes R, Moulton LH: Cluster Randomised Controlled Trials. New York: Chapman &Hall/CRC Press; 2009.
• [8]US Census Bureau: Technical paper 63RV: current population survey - design and methodology. TP63RV 2002, 14–18. Available at http://www.census.gov/prod/2002pubs/tp63rv.pdf webcite. Accessed on October 02, 2013
• [9]Hayes RJ, Benett S: Simple size calculation for cluster-randomised trials. Int J Epidemiol 1999, 28(2):319-326.
• [10]Eldridge SM, Ukoumunne OC, Carlin JB: The intra-cluster correlation coefficient in cluster randomized trials: a review of definitions. Int Stat Rev 2009, 77(3):378-394.
• [11]Passini R Jr, Tedesco RP, Marba ST, Cecatti JG, Guinsburg R, Martinez FE, Nomura ML, Brazilian Network of Studies on Reproductive and Perinatal Health: Brazilian multicenter study on prevalence of preterm birth and associated factors. BMC Pregnancy Childbirth 2010, 10:22. BioMed Central Full Text
• [12]Tedesco RP, Passini R Jr, Cecatti JG, Camargo RS, Pacagnella RC, Sousa MH: Estimation of preterm birth rate, associated factors and maternal morbidity from a Demographic and Health Survey in Brazil. Matern Child Health J 2013, 17(9):1638-1647.
• [13]SPSS for Windows: Release 20.0. New York: SPSS Inc; 2011.
• [14]StataCorp: Stata Statistical Software: Release 7. College Station, TX: StataCorp LP; 2001. [College Station]
• [15]Campbell MK, Fayers PM, Grimshaw JM: Determinants of the intracluster correlation coefficient in cluster randomised trials: the case of implementation research. Clin Trials 2005, 2:99-107.
• [16]Taljaard M, Donner A, Villar J, Wojdyla D, Velazco A, Bataglia V, Bataglia V, Faundes A, Langer A, Narváez A, Valladares E, Carroli G, Zavaleta N, Shah A, Campodónico L, Romero M, Reynoso S, de Pádua KS, Giordano D, Kublickas M, Acosta A, World Health Organization 2005 Global Survey on Maternal and Perinatal Health Research Group: Intracluster correlation coefficients from the WHO Global Survey on Maternal and Perinatal Health: implications for implementation research. Paediat Perinatal Epidemiol 2005, 2008(22):117-125.
• [17]Pagel C, Prost A, Lewycka S, Das S, Colbourn T, Mahapatra R, Azad K, Costello A, Osrin D: Intracluster correlation coefficients and coefficients of variation for perinatal outcomes from five cluster-randomised controlled trials in low and middle-income countries: results and methodological implications. Trials 2011, 12:151. BioMed Central Full Text
• [18]Piaggio G, Carroli G, Villar J, Pinol A, Bakketeig L, Lumbiganon P, Bergsjø P, Al-Mazrou Y, Ba'aqeel H, Belizán JM, Farnot U, Berendes H, WHO Antenatal Care Trial Research Group: Methodological considerations on the design and analysis of an equivalence stratified cluster randomization trial. Stat Med 2001, 20:401-416.
• [19]Campbell SM, Braspenning J, Hutchinson A, Marshall M: Research methods used in developing and applying quality indicators in primary care. Qual Safe Health Care 2002, 11:358-364.
• [20]Haddad SM, Sousa MH, Cecatti JG, Parpinelli MA, Costa ML, Souza JP, and for the Brazilian Network for Surveillance of Severe Maternal Morbidity Group: Intraclass correlation coefficients in the Brazilian network for surveillance of severe maternal morbidity study. BMC Pregnancy Childbirth 2012, 12:101. BioMed Central Full Text
• [21]Brazilian Ministry of Health: National Registry of Health Facilities. 2013. Available at http://cnes.datasus.gov.br/Lista_Tot_Es_Estado.asp. Accessed on November 27th, 2013
• [22]Brazilian Ministry of Health: SINASC – National Information System on Live Births. 2011. Available at http://tabnet.datasus.gov.br/cgi/tabcgi.exe?sinasc/cnv/nvuf.def. Accessed on November 27th, 2013