Background: Adolescents who rely on social aid networks tend to be more socially competent and enjoy higher levels of quality of life than those who interact only with their own limited groups of family and friends. In this light, the present study aimed to measure social capital and analyse its possible relation to adolescents’ quality of life. Methods: This is a cross-sectional analytical study with 363 adolescents from the Brazilian NGO. The instruments used included a short Portuguese version of the Integrated Questionnaire to Measure Social Capital (SC-QI) from the World Bank and its abbreviated Portuguese version from the World Health Organization Quality of Life Bref (WHOQoL-Bref) used to measure the quality of life. To measure social capital, the present study chose to use a segmentation analysis, along with the Two-Step Cluster method, applying Euclidian distance and the criteria of centroid aggregation. The Mann-Whitney test was used to compare the scores of WHOQoL-Bref domains among the clusters, at a significance level of 5%. Results: The segmentation analysis resulted in two clusters, with 160 (44.1%) adolescents classified as Low Social Capital (LSC) and 178 (49%) classified as High Social Capital (HSC). Participation in activities for the good of the community (p < 0.001), opinion regarding the differences between people in the community (p = 0.002), and number of community meetings (p < 0.001) constituted the decisive variables for determining the separation of the clusters. When quality of life among the newly formed clusters was compared, the highest average score in the HSC cluster was found in the Psychological Domain (75.4 ± 11.9), whereas in the LSC cluster, the highest average score was found in the Physical Domain (74.6 ± 12.6). Lower quality of life scores was found in the environmental domain for both the LSC clusters (51.3 ± 14.0) and the HSC clusters (54.7 ± 15.5). This difference proved to be statistically significant (p = 0.009). Conclusions: The results showed that adolescents with higher social capital also presented higher scores concerning quality of life. For the studied population, a positive relation between the two concepts was verified.
 Baum, F.E., Bush, R.A., Modra, C.C., Murray, C.J., Cox, E.M., Alexander, K.M. and Potter, R.C. (2000) Epidemiology of participation: An Australian community study. Journal of Epidemiology & Community Health, 54, 414- 423. doi:10.1136/jech.54.6.414
 Nilsson, J., Rana, A.K.M.M. and Kabir, Z.N. (2006) Social capital and quality of life in old age: Results from a cross-sectional study in rural Bangladesh. Journal of Aging and Health, 3, 419-434. doi:10.1177/0898264306286198
 Barker, G. (2007) Adolescents, social support and helpseeking behavior: An international literature review and program consultation with recommendations for action. Department of Child and Adolescent Health and Development, World Health Organization: WHO discussion papers on adolescence.
 Edwards, T.C., Huebner, C.E., Connell, F.A. and Patrick, D.L. (2002) Adolescent quality of life, part I: Conceptual and measurement model. Journal of Adolescence, 25, 275-286. doi:10.1006/jado.2002.0470
 Drukker, M., Kaplan, C., Schneiders, J., Feron, F.J.M. and van Os, J. (2006) The wider social environment and changes in self-reported quality of life in the transition from late childhood to early adolescence: A cohort study. BMC Public Health, 6, 133. doi:10.1186/1471-2458-6-133
 Polinder, S., Haagsma, J.A., Belt, E., Lyons, R.A., Erasmus, V., Lund, J., et al. (2010) A systematic review of studies measuring health-related quality of life of general injury populations. BMC Public Health, 10, 783. doi:10.1186/1471-2458-10-783
 Borges, C.M., Campos, A.C.V., Vargas, A.M.D., Ferreira, E.F. and Kawachi, I. (2010) Social capital and self-rated health among adolescents in Brazil: An exploratory study. BMC Research Notes, 3, 338. http://www.biomedcentral.com/1756-0500/3/338
 Patussi, M.P., Hardy, R. and Sheiham, A. (2006) Neighborhood social capital and dental injuries in Brazilian adolescents. American Journal of Public Health, 96, 1462- 1468. doi:10.2105/AJPH.2005.066159
 Patussi, M.P., Hardy. R. and Sheiham, A. (2006) The potential impact of neighborhood empowerment on dental caries among adolescents. Community Dentistry and Oral Epidemiology, 34, 344-350. doi:10.1111/j.1600-0528.2006.00283.x
 Fleck, M.P.A., Louzada, S., Xavier, M., Chachamovich, E., Vieira, G., Santos, L., et al. (2000) Application of the Portuguese version of the abbreviated instrument of quality life WHOQoL-bref. Revista de Saúde Pública, 2, 178- 183. doi:10.1590/S0034-89102000000200012
 Grootaert, C., Narayan, D., Jones, V.N. and Woolcock, M. (2003) Integrated questionnaire for the measurement of social capital (SC-IQ). World Bank, Washington DC.
ara%20medir%20Capital% 20Social% 20Banco%20Mundial.pdf
 Hair, J.F., Black, W.C., Babin, J.B. and Anderson, R.E., Tatham, R.L. (2009) Segmentation analysis. In: Hair, J.F., Black, W.C., Babin, J.B., Anderson, R.E. and Tatham, R.L., Eds., Multivariate Data Analysis, 6th Edition, Prentice-Hall, Upper Saddle River, 427-481.
 Jozefiak, T., Larsson, B. and Wichstrøm, L. (2009) Changes in quality of life among Norwegian school children: A six-month follow-up study. Health and Quality of Life Outcomes, 7, 7. doi:10.1186/1477-7525-7-7
 Brown, D.W., Balluz, L.S., Heath, G.W., Moriarty, D.G., Ford, E.S., Giles, W.H., et al. (2003) Associations between recommended levels of physical activity and health- related quality of life findings from the 2001 Behavioral Risk Factor Surveillance System (BRFSS) survey. Preventive Medicine, 5, 520-528. doi:10.1016/S0091-7435(03)00179-8
 Delaney, L. and Keaney, E. (2005) Sport and social capital in the United Kingdom: Statistical evidence from national and international survey data. Economic and Social Research Institute, Institute for Public Policy Research, Dublin.
 Zullig, K.J., Valois, R.F. and Drane, J.W. (2005) Adolescent distinctions between quality of life and self-rated health in quality of life research. Health Qual Life Outcomes, 3, 64. doi:10.1186/1477-7525-3-64
 Rajmil, L., Palacio-Vieira, J.A., Herdman, M., López- Aguilà, S., Villalonga-Olives, E., Valderas, J.M., et al. (2009) Effect on health-related quality of life of changes in mental health in children and adolescents. Health and Quality of Life Outcomes, 7, 103. doi:10.1186/1477-7525-7-103
 Duke, N.N., Skay, C.L., Pettingell, S.L. and Borowsky, I.W. (2009) From adolescent connections to social capital: Predictors of civic engagement in young adulthood. Journal of Adolescent Health, 44, 161-168. doi:10.1016/j.jadohealth.2008.07.007
 Modie-Moroka, T. (2009) Does level of social capital predict perceived health in a community? A study of adult residents of low-income areas of Francistown, Botswana. Journal of Health, Population and Nutrition, 27, 462-476. doi:10.3329/jhpn.v27i4.3390
 Drukker, M., Kaplan, C.D., Feron, F.J.M. and Van Os, J. (2003) Children’s health-related quality of life, neighbourhood socio-economic deprivation and social capital. A contextual analysis. Social Science & Medicine, 57, 825-841. doi:10.1016/S0277-9536(02)00453-7
 Morrow, V. (2001) Using qualitative methods to elicit young people’s perspectives on their environments: Some ideas for community health initiatives. Health Education Research, 16, 255-268. doi:10.1093/her/16.3.255
 Sherbourne, C.D., Meredith, L.S., Rogers, W. and Ware Jr., J.E. (1992) Social support and stressful life events: Age differences in their effects on health-related quality of life among the chronically ill. Quality of Life Research, 1, 235-246. doi:10.1007/BF00435632
 Villalonga-Olives, E., Rojas-Farreras, S., Vilagut, G., Palacio-Vieira, J.A., Valderas, J.M., Herdman, M., et al. (2010) Impact of recent life events on the health related quality of life of adolescents and youths: The role of gender and life events typologies in a follow-up study. Health and Quality of Life Outcomes, 8, 71. doi:10.1186/1477-7525-8-71
 Aro, H., Hänninen, V. and Paronen, O. (1989) Social support, life events and psychosomatic symptoms among 14 - 16-year-old adolescents. Social Science & Medicine, 29, 1051-1056. doi:10.1016/0277-9536(89)90015-4
 Caughy, M.O.B., O’Campo, P.J. and Muntaner, C. (2003) When being alone might be better: neighborhood poverty, social capital, and child mental health. Social Science & Medicine, 57, 227-237. doi:10.1016/S0277-9536(02)00342-8
 Giordano, G.N. and Lindstrom, M. (2010) The impact of changes in different aspects of social capital and material conditions on self-rated health over time: A longitudinal cohort study. Social Science & Medicine, 70, 700-710. doi:10.1016/j.socscimed.2009.10.044
 Kim, D. and Kawachi, I. (2006) A multilevel analysis of key forms of community—and individual—level social capital as predictors of self-rated health in the United States. Journal of Urban Health: Bulletin of the New York Academy of Medicine, 5, 813-826.
 Boyce, W.F., Davies, D., Gallupe, O. and Shelley, D. (2008) Adolescent risk taking, neighborhood social capital, and health. Journal of Adolescent Health, 43, 246-252. doi:10.1016/j.jadohealth.2008.01.014
 Baumann, C., Erpelding, M.L., Perret-Guillaume, C., Gautier, A., Régat, S., Collin, J.F., et al. (2011) Health- related quality of life in French adolescents and adults: Norms for the DUKE health profile. BMC Public Health, 11, 401. doi:10.1186/1471-2458-11-401