Predictors of drop-out in a multi-centre longitudinal study of participation and quality of life of children with cerebral palsy
1 Institute of Health and Society, Newcastle University, Royal Victoria Infirmary, Newcastle upon Tyne, NE1 4LP, UK
2 Klinik für Kinder und Jugendmedizin, Universitätsklinikum Schleswig-Holstein, Ratzeburger Allee 160, Lübeck, 23538, Germany
3 Inserm, UMR 1027, Toulouse, F-31073, France
4 The Queen Silvia Children’s Hospital, Göteborg University, Göteborg, S-41685, Sweden
5 SIIM-Pole Exploitation, Université Joseph Fournier, CHU de Grenoble BP 217, Grenoble cedex, 9 38043, France
6 Enable Ireland, Lavanagh Centre, Ballintemple, Cork, Ireland
7 Azienda Sanitaria Locale Viterbo, Viale Trento 18 H, Viterbo, 01100, Italy
8 National Institute of Public Health, Oster Farimagsgade 5, Copenhagen, 1353, Denmark
9 School of Nursing & Midwifery, Queen’s University Belfast, 21 Stranmillis Road, Belfast, BT9 5AF, UK
10 Institute of Health and Society, Newcastle University, William Leech Building, Newcastle upon Tyne, NE2 4HH, UK
BMC Research Notes 2012, 5:300 doi:10.1186/1756-0500-5-300Published: 15 June 2012
SPARCLE is a study across nine European regions which examines the predictors of participation and quality of life of children with cerebral palsy. Children and their families were initially interviewed in 2004/2005 when the children were aged 8–12 years (SPARCLE1); they were approached again in 2009/2010 at age 13–17 years (SPARCLE2). The objective of this report is to assess potential for bias due to family non-response in SPARCLE2. Logistic regression was used to assess whether socio-demographic factors, parental stress and child impairment were related to non-response, both overall and by category (failure to trace families, death of child, traced families declining to participate).
Of the 818 families who participated in SPARCLE1, 224/818 (27%) did not participate in SPARCLE2. 51/818 (6%) were not traced. Among the 767 traced families, 32/767 (4%) children with cerebral palsy had died, seven children had been incorrectly diagnosed as having cerebral palsy, thirteen families had moved out of the region and one family had language problems. Of the remaining 714 families, 120/714 (17%) declined to participate. Drop-out between SPARCLE1 and SPARCLE2 varied significantly between regions; families were more difficult to trace and more likely to decline to participate if the parents’ educational qualifications, as recorded in SPARCLE1, were lower; they were also more likely to decline to participate if SPARCLE1 recorded that they were more stressed or if they had not completed a SPARCLE1 stress questionnaire.
To reduce the risk of bias, all SPARCLE2 analyses should allow for factors (region and walking ability) which determined the sampling strategy, either by adjusting for these factors or by using sampling weights. Further analyses should be performed, adjusting for additional factors that were associated with non-response: parents' educational qualifications, family structure and parental stress. To allow for differential non-response in studies which sample from population registers, such registers should routinely record socio-demographic information.