Factors associated with functional disability of elderly in Brazil: a multilevel analysis


Factores asociados a la incapacidad funcional de los ancianos en Brasil: análisis multinivel



Luciana Correia AlvesI; Iúri da Costa LeiteII; Carla Jorge MachadoIII

ICentro de Saúde Escola Germano Sinval Faria. Escola Nacional de Saúde Pública Sergio Arouca (ENSP). Fundação Oswaldo Cruz (Fiocruz). Rio de Janeiro, RJ, Brasil
IIDepartamento de Epidemiologia e Métodos Quantitativos em Saúde. ENSP. Fiocruz. Rio de Janeiro, RJ, Brasil
IIICentro de Desenvolvimento e Planejamento Regional. Faculdade de Ciências Econômicas. Universidade Federal de Minas Gerais. Belo Horizonte, MG, Brasil





OBJECTIVE: To analyze the influence of demographic, socioeconomic, health, and contextual factors of the Brazilian federation units on the functional disability of the elderly.
METHODS: Cross-sectional study based on data from the 2003 PNAD (Brazilian National Household Survey), of IBGE (Brazilian Institute of Geography and Statistics) and Ipea (Institute of Applied Economic Research). The sample was composed of 33,515 individuals aged 60 years and older. The dependent variable was functional disability, measured by difficulty in climbing slopes or stairs. The independent variables were divided into two levels: individual (demographic, socioeconomic and health-related characteristics) and contextual (Gini Index and Gross Domestic Product per capita by Brazilian state in 2000). A multinomial and multilevel logistic regression model was utilized in order to estimate the effect of the independent variables on the functional disability of the elderly.
RESULTS: Functional disability was associated with demographic, socioeconomic and health factors. At the individual level, sex, level of schooling, income, occupation, self-perception of health and chronic diseases were the factors that were most strongly related to functional disability. At the contextual level, income inequality proved to exert an important influence.
CONCLUSIONS: Self-perception of health is the factor that is most strongly related to the functional disability of the elderly in Brazil, followed by chronic diseases. Sex, occupation, level of schooling and income are also highly associated with it. Actions that approach the main factors associated with functional disability can contribute significantly to the well-being and quality of life of the elderly.

Descriptors: Aged. Frail Elderly. Functional Capacity. Socioeconomic Factors. Multilevel Analysis. Cross-Sectional Studies. Health of the Elderly. Quality of Life.


OBJETIVO: Analizar la influencia de los factores demográficos, socioeconómicos, de condiciones de salud y del contexto de las unidades de la federación en la incapacidad funcional de los ancianos.
MÉTODOS: Estudio transversal que utilizó datos de la Pesquisa Nacional por Muestra de Domicilio (PNAD) de 2003, del Instituto Brasilero de Geografía y Estadística y del Instituto de Pesquisa Económica Aplicada. La muestra fue constituida de 33.515 individuos con 60 años o más de edad. La variable dependiente fue la incapacidad funcional, medida por la dificultad para subir ladera o escalera. Las variables independientes fueron divididas en dos niveles: individual (características demográficas, socioeconómicas y relativas a la salud) y de contexto (Índice de Gini y Producto Interno Bruto per capita por unidad federación en 2000). Un modelo de regresión logística multinomial multinivel fue utilizado para estimar el efecto de las variables independientes en la incapacidad funcional de los ancianos.
RESULTADOS: La incapacidad funcional fue asociada con factores demográficos, socioeconómicos y de salud. En nivel individual, el sexo, la educación, la renta, la ocupación la autopercepción de salud y las enfermedades crónicas fueron los factores más fuertemente relacionados. En nivel de contexto, la desigualdad de renta exhibió una importante influencia.
CONCLUSIONES: La autopercepción de salud es el factor más fuertemente relacionado con la incapacidad funcional de los ancianos en Brasil, seguido por las enfermedades crónicas. Sexo, ocupación, escolaridad y renta también son altamente asociados. Acciones que abordan los principales factores asociados a la incapacidad funcional pueden contribuir significativamente para el bienestar y calidad de vida de los ancianos.

Descriptores: Anciano. Anciano Frágil. Acondicionamiento Físico. Capacidad funcional. Factores Socioeconómicos. Análisis Multinivel. Estudios Transversales. Salud del Anciano. Calidad de Vida




Brazil has been undergoing a quick and sharp process of aging and extension of the population's longevity. With the acceleration of this process, there is an increase in the prevalence of chronic-degenerative diseases and of functional disability.1

Functional disability can be defined by the individual's difficulty or need of help concerning the execution of basic or more complex daily tasks that are necessary for an independent life in the community, like, for example, mobility-related tasks.2 Although the presence of chronic diseases is important, their functional consequences have implications that are more visible and perceptible to the elderly, since functional loss causes greater vulnerability and dependence in old age.12

The functional disability of the elderly can be determined by activities of daily living (ADL), by instrumental activities of daily living (IADL) and by physical mobility.2

Individual factors have been viewed as responsible for the functional disability process. Previous studies have shown that functional decline is related to demographic, socioeconomic and health factors.1,4,5,6 However, few studies in Brazil focus on the relationship of the determinants of functional disability among the elderly.8,19,24

At the contextual level, socioeconomic conditions can explain regional variations and the great diversity of the levels of health and functional disability among the elderly. Income inequality can cause contextual or extra-individual effects on the social environment that affect health. To Porell & Miltiades21 (2002), the impact of adverse socioeconomic conditions on individuals' health is higher in regions with highly unequal income distribution. According to Kaplan et al13 (1996), high income inequality measured in the national, state or community level is associated with worse population's health.

Brazil is among the countries with the highest degrees of social inequality. A study using data from Pesquisa Nacional por Amostra de Domicílios (PNAD - Brazilian National Household Survey) indicated that the functional capacity of the elderly is strongly influenced by the socioeconomic situation.15 It is likely that individuals living in areas with better socioeconomic conditions have greater access to medical goods and services and, consequently, are capable of maintaining good health conditions and functional capacity over time.21 Nevertheless, there are no studies in Brazil that investigate the relations between socioeconomic inequalities at the level of federation units (states and the Federal District), important geographic spaces for application of public policies, and functional disability of the elderly.

The aim of the present study was to analyze the influence of demographic, socioeconomic, health and contextual factors of the federation units on the functional disability of the elderly.



Cross-sectional study based on data from PNAD-2003, from Instituto Brasileiro de Geografia e Estatística (IBGE - Brazilian Institute of Geography and Statistics)ª and Instituto de Pesquisa Econômica Aplicada (IPEA - Institute of Applied Economic Research).b In 1998, PNAD included in its questionnaire a health supplement whose information should be collected every five years, and 2003 was the most recent available information.

The present study included individuals aged 60 years or older, whose data were obtained by PNAD by means of home interviews. Overall, 1,527 elderly people who did not answer the questions regarding the study's variables were excluded. The studied sample was composed of 33,515 elderly individuals.

The dependent variable was functional disability. To measure it, the physical mobility variable "ability to climb slopes or stairs" was used, considered a robust indicator of future functional decline among the elderly.12 In addition, the choice of the physical mobility indicator to the detriment of the ADL derives from its capacity to detect an early stage of functional losses, enabling the discrimination of disability in the community.17 The interviewee answered the following question: "Do you usually have difficulty in climbing slopes or stairs?" Four categories were used in the functional disability classification: does not have difficulty, has low level of difficulty, has high level of difficulty and cannot do it.

The independent variables were subdivided into two levels: individual and contextual. At the individual level, the variables were classified into three blocks: demographic, socioeconomic, and health. The demographic variables were: age (considered as continuous because capacity loss has a direct relationship to aging), sex, family arrangement (lives alone and lives with someone), race/color (white, black and mixed ethnicity) and household situation (urban and rural). In PNAD, individuals classify themselves in terms of race/color as: white, black, yellow, mixed ethnicity and indigenous. Indigenous individuals, yellow ones and those who did not declare their race/color were excluded because the relative frequency was below 1%. The socioeconomic variables were: level of schooling, (no schooling, 1-4, 5-8, 9-11 and 12 years of schooling or more), monthly family income (lower than one minimum salary, one to three, three to five, five to ten and ten or more) and occupation (occupied and unoccupied). Minimum salary refers to the value it had on April 2003 (R$240.00). The included health variables were: self-perception of health (very good, good, regular, poor and extremely poor), self-reported presence of arthritis/rheumatism, cancer, hypertension, diabetes, bronchitis/asthma, heart disease, chronic renal failure, depression, spinal column problems, tuberculosis, tendinitis/tenosynovitis and cirrhosis (dichotomized into yes and no), hospitalizations in the last 12 months (yes and no) and affiliation to a private health plan (yes and no).

The independent contextual variables that were included were: Gini Indexb and Gross Domestic Product (GDP)c per capita by federation unit (FU) in 2000.

According to Pinheiro & Torres20 (2006), individuals living in the same FU are more similar concerning health problems when compared to those living in another FU, because they are submitted to the same context (socioeconomic conditions, cultural factors, among others). Thus, inside the FU, observations would not be independent and there would be violation of the presuppositions of the traditional regression models. In light of the fact that the data structure is hierarchical and the response variable has four categories, to estimate the association between functional disability and the demographic, socioeconomic and health variables, the multilevel multinomial logistic regression model was employed, with the first level represented by the individuals, and the second, by the FU.9

Initially, a univariate multinomial logistic regression analysis was carried out with the variables of the individual level. The statistically significant variables (p<0.25) in the univariate regression analysis were selected for multivariate analysis. In the multivariate analysis, the variables of the individual level were included first, followed by the variables of the contextual level with the fixed coefficients. The evaluation of the effect of the contextual variables on functional disability was carried out through the analysis of the statistical significance (p<0.05) of its coefficient and through the reduction in the random effect variance, in comparison with the model that has only the individuals' characteristics.

The results of the final model (individual and contextual variables) were interpreted in probabilities, calculated for each statistically significant variable (p<0.05), and the other variables were centered on the mean.23 The software MLwiN was used for data analysis.22



The elderly individuals' age varied from 60 to 106 years (Table 1), and the mean and median ages were 69.8 and 68 years, respectively (SD = 7.7). The population was predominantly female (56.1%) and 87.1% of the elderly lived with someone; 84.2% lived in urban areas; 55.7% referred to their color as white; 37.8% did not have any schooling; 37.5% earned from one to three minimum salaries; 32.8% were occupied. As for health aspects, 35% perceived their health as good; 12.7% reported hospitalization in the last 12 months and 28% had a private health plan. Arterial hypertension was the most frequent chronic disease (48.9%), followed by spinal column problems (36.8%), arthritis/rheumatism (28.5%), heart disease (17.4%) and diabetes (12.9%) (Table 1).

The estimates of the coefficients of the fixed and random effects of the models with the variables of the individual level and final model are in Table 2. The model with the individual level variables showed that part of the variability in the probability of the elderly individual to have low level of difficulty, high level of difficulty and not being able to climb slopes or stairs was explained by the level of the FU (sð2j =0.054; 0.091; 0.150; p<0.05; respectively).

After controlling the factors of the contextual level, there was reduction of 13%, 36.3% and 36.7% in the random effect variance, which continued to be statistically different from zero for the three categories of the dependent variable, indicating that there still was variability in the contextual level, which might be reduced with the additional inclusion of variables of this level in the model. The inclusion of the contextual variables in the model did not cause important modifications in the estimates of the coefficients of the individual variables.

The interpretation of the final model was carried out in terms of probabilities (Table 3). The probability of the individual to be able to climb slopes or stairs decreased as age increased (0.60 at 60 years of age and 0.24 at 85 years) and increased in the category cannot do it (0.04 at 60 years of age and 0.21 at 85 years). The female sex showed higher probability to have high level of difficulty (0.21) and not to be able to do it (0.09) compared to men (0.15 and 0.07, respectively). The probability of the elderly who lived with someone to fail in the execution of the activity was higher compared to those who lived alone (0.08 and 0.06, respectively). As for the household situation, the elderly who lived in the rural area presented higher probability to fail to do it compared to those living in the urban area (0.10 and 0.08, respectively). Having black and mixed (black and white) skin color reduced the probability of the elderly to fail to climb slopes or stairs (0.07). As for level of schooling and income, as the levels increased, the probability of the elderly individuals to be able to carry out the activity increased. Income lower than one minimum salary increased the probability of failure in the accomplishment of the activity (0.09). The occupied elderly individuals had lower probability to present high level of difficulty (0.15) in relation to the unoccupied individuals. The unoccupied individuals, in turn, presented high probability (0.11) of failure, compared to the occupied ones (0.04).

Concerning the health indicators, the elderly who self-perceived their health as poor (0.25) and extremely poor (0.43) had much higher propensity to fail in carrying out the activity. Regarding chronic diseases, the absence of spinal column problems increased the probability (0.49) of success in the accomplishment of the activity. Those suffering from arthritis, diabetes, bronchitis, hypertension, heart disease, chronic renal failure, depression and tuberculosis presented increased probability to have high level of difficulty (probabilities of 0.24; 0.21; 0.27; 0.20; 0.25; 0.22; 0.21; 0.32; respectively) compared to individuals without those diseases (probabilities of 0.16; 0.18; 0.18; 0.17; 0.17; 0.18; 0.18; 0.18; respectively). The presence of cancer increased the probability to fail to accomplish the activity (0.11) compared to those who did not suffer from it (0.08). Tendinitis and cirrhosis did not have a statistically significant association. In the case of occurrence of hospitalizations in the last 12 months, the elderly had high probability of high level of difficulty (0.22) and of failure in climbing slopes or stairs (0.15) compared to those who were not hospitalized (0.18 and 0.07, respectively). Elderly individuals who owned a health plan had lower probability to present high level of difficulty (0.16) in accomplishing the activity compared to those who did not have a health plan (0.19).

In relation to the contextual variables, the Gini Index in 2000 presented a statistically significant association with the functional disability of the elderly. The elderly who lived in FU with greater levels of economic inequality presented higher probabilities to have high level of difficulty (0.21) or to fail (0.09) to climb slopes or stairs compared to the elderly who lived in States with lower economic disadvantages (0.16 and 0.07, respectively). The GDP in 2000 did not show a statistically significant effect on the functional disability of the elderly.

Table 4 presents the probabilities for the sex variable categories, taking into account different levels of the random effect on the category having high level of difficulty. In areas located in the mean, the probability of a woman to present high level of difficulty proved to be 45% higher compared to that of men (0.214/0.147). However, this probability may increase considerably if we compare women living in areas located two SD above the mean with men living in areas located two SD below the mean (218%). Due to the overlap, the probability to present high level of difficulty may be higher among men if we compare, for example, men living in FU two SD above the mean (0.218) with women living in FU located two SD below the mean (0.144).



The multinomial logistic regression model enabled to disaggregate functional capacity into more than two categories.1 Some aspects, however, limit the use of these models. Firstly, functional disability might be understood as ordered and the risk might be estimated in relation to the immediately previous category. Nevertheless, even though an underlying order exists, the comparison between types of disability and full capacity allows to assess the effect of the several variables, having the same baseline for comparison, which makes sense because, ideally, all the elderly might be capable. Another important aspect of the modeling process was the utilization of multilevel models, which allowed to estimate more accurately the parameters associated with the individual and contextual variables simultaneously.

At the individual level, the results indicate that functional disability was highly associated with sex. Elderly women had higher probability to present higher functional loss than men. These results corroborate those found by Giacomin et al8 (2008). Some hypotheses might explain this difference. The first one is associated with women's longer survival. The second refers to the higher prevalence of non-fatal incapacitating conditions among women. The third hypothesis would be the women's ability to report a higher number of health conditions compared to men of the same age.18

The present study showed that aging increased the probability of the elderly to present functional disability, in agreement with previous studies.11,16

Black and mixed (black and white) race/color was a protective factor of functional disability, contradicting the findings of Guralnik & Kaplan10 (1989) in the USA. It is possible that black and mixed ethnicity elderly individuals in our study were healthier compared to whites, given that those with worse health conditions may have experimented higher mortality rates. It is important to remember that in Brazil, race/color is directly associated with the individual's socioeconomic situation.

Living in urban areas was a protective factor for functional disability, contradicting results found by Parahyba et al19 (2005) in Brazil. It is likely that the elderly who live in urban areas present better life conditions, greater availability and access to prevention and primary or specialized medical assistance services.

Living with someone was a determinant factor for functional disability. Elderly individuals who live with someone are more likely not to be able to climb slopes or stairs compared to those who live alone. Our findings corroborate those of Rosa et al24 (2003), suggesting that elderly people who live alone are probably healthier and more independent.

The higher the level of schooling and income, the lower the probability of the elderly person to report a worse functional capacity, which confirms previous findings.4,15 Schooling brings diverse advantages to health because it influences psychosocial and behavioral factors.7 Elderly individuals with higher level of schooling are less likely to be exposed to the risk factors for diseases and to submit themselves to inadequate working conditions. Higher level of schooling favors the access to: information, lifestyle modifications, adoption of healthy habits and visits to healthcare services.25 Probably, poorer elderly individuals attend the healthcare services less frequently, and have less access to treatments and medicines. Occupation also exerts a protective effect. The occupied elderly person is less likely to present worse functional capacity. These results are in agreement with those reported by Cheng et al6 (2002) in which occupied elderly individuals present few difficulties in activities of daily living when compared to those who do not work. It is reasonable to suppose that elderly people who work are more independent and healthier.

Concerning their self-perception of health, the probability of an increase in the dependence degree was higher for the elderly who rated their health as poor, confirming previous findings.14

Chronic diseases had a strong influence on the functional capacity of the elderly. Alves et al1 (2007) investigated the influence of chronic diseases on the functional capacity of the inhabitants of the municipality of São Paulo, southeast of Brazil, in 2000, observing that the chronic conditions had a significant influence on functional dependence and that heart disease, pulmonary disease, hypertension and arthropathy presented the greatest effects.

As for hospitalizations, the associations that were found coincided with those of the study carried out by Boyd et al5 (2005), in which the elderly became more vulnerable to functional decline and dependence after hospitalization.

An important relationship was observed between affiliation to health plan and functional disability. The elderly affiliated to health plans had lower probability to fail to climb slopes or stairs. Although we have not found studies on the relationship between health plan and functional disability of the elderly, it is probable that individuals with health plan attend the healthcare services more frequently and present higher adherence to treatments, which contribute to improve their functional capacity.

The results showed an effect of the income inequality of the FU on the functional disability of the elderly, even when controlled by the average income level (GDP). Although there are many studies about the relationship between income inequality and health status, this kind of investigation is still rare in Brazil. The main results indicate lack of relationship between income inequality and health status. However, Noronhad (2005) found that the individuals who live in unequal places have smaller chances of being healthy. This effect would express the characteristics associated with the context in which the individual is inserted rather than shortage of material resources or the lower purchasing power of poorer individuals.

Other findings of the present study show that the elderly who live in more unequal states have higher probability to present functional loss. The mechanisms through which income inequality affects functional disability in Brazil can be explained taking into account the particularities of the Brazilian reality. The country presents one of the worst income distributions in the world and is characterized by the presence of individual and regional inequalities, which defines, on one side, richer cities and regions, with socioeconomic and health indicators that are similar to those of more developed economies, and on the other side, very poor cities and regions, like those observed in the FU of the North and Northeast of Brazil. The presence of these inequities results in unequal distribution of resources across the cities and, consequently, unequal access to goods and services that are important to the level of health of the individual and of the population, such as healthcare services, education and basic sanitation.3

The investigation of the relationship between functional disability and individual and contextual factors related to the economic situation is relevant, due to the deep socioeconomic disparities observed among individuals and among states. We did not find in the Brazilian literature any references to studies about this kind of analysis that assesses the effect of income inequality on functional disability in the FU, and also analyzes the characteristics of the individuals and of the context, considering the hierarchic structure of the data.

Even after controlling through variables of the contextual level, we verified the existence of a variability that still needs to be explained. Thus, future research could investigate other important aspects of the contextual level related to functional disability of the elderly in Brazil.

As for the study's limitations, the few works about multilevel analysis and functional disability in the international literature, the lack of studies in Brazil, the difference concerning the context variables used in the analysis hindered the comparison between the present findings. Another limitation refers to the cross-sectional design, which prevented causal inferences.

The identification of factors associated with the functional disability of the elderly provides relevant elements for prevention and intervention measures and is fundamental in the present society. The study suggests that policies focusing on the reduction in social and economic inequalities should be encouraged, like for example: guaranteeing education in the early phases of life and the permanence of the elderly in the labor market. Finally, the present study strengthens the importance of strategies targeted at the maintenance of health and of a life without disability, with preventive actions and the organization of the health system so as to meet the real needs of this portion of the population, which is the one that has the highest growth rate in Brazil. Thus, the individuals would be able to age in a healthier way, living their additional years of life with higher quality.



1. Alves LC, Leimann BCQ, Vasconcelos MEL, Carvalho MS, Vasconcelos AGG, Fonseca TCO, et al. A influência das doenças crônicas na capacidade funcional dos idosos do Município de São Paulo, Brasil. Cad Saude Publica. 2007;23(8):1924-930. DOI:10.1590/S0102-311X2007000800019        

2. Alves LC, Leite IC, Machado CJ. Conceituando e mensurando a incapacidade funcional da população idosa: uma revisão de literatura. Cienc Saude Coletiva. 2008;13(4):1199-207. DOI:10.1590/S1413-81232008000400016        

3. Barros RP, Mendonça R. Os determinantes da desigualdade no Brasil. In: Instituto de Pesquisa Econômica Aplicada. A economia brasileira em perspectiva, 2006. Rio de Janeiro; 1996. v.2, p.421-73.         

4. Berkman CS, Gurland BJ. The relationship among income, other socioeconomic indicators, and functional level in older persons. J Aging Health. 1998;10(1):81-98. DOI:10.1177/089826439801000105        

5. Boyd CM, Xue QL, Simpson CF, Guralnik JM, Fried LP. Frailty, hospitalization, and progression of disability in a cohort of disabled older women. Am J Med. 2005;118(11):1225-31. DOI:10.1016/j.amjmed.2005.01.062        

6. Cheng YH, Chi I, Boey KW, Ko LS, Chou KL. Self-rated economic condition and the health of elderly persons in Hong Kong. Soc Sci Med. 2002;55(8):1415-24. DOI:10.1016/S0277-9536(01)00271-4        

7. Elo IT, Preston SH. Educational differentials in mortality: United States, 1979-85. Soc Sci Med. 1996;42(1):47-57. DOI:10.1016/0277-9536(95)00062-3        

8. Giacomin KC, Peixoto SV, Uchoa E, Lima-Costa MF. Estudo de base populacional dos fatores associados à incapacidade funcional entre idosos na Região Metropolitana de Belo Horizonte, Minas Gerais, Brasil. Cad Saude Publica. 2008;24(6):1260-70. DOI:10.1590/S0102-311X2008000600007        

9. Goldstein H. Multilevel statistical models. London: Arnold; 2003. (Kendall's library of statistics, 3).         

10. Guralnik JM, Kaplan GA. Predictors of healthy aging: prospective evidence from the Alameda County study. Am J Public Health. 1989;79(6):703-8. DOI:10.2105/AJPH.79.6.703        

11. Guralnik JM, LaCroix AZ, Abbott RD, Berkman LF, Satterfield S, Evans DA, et al. Maintaining mobility in late life. I. Demographic characteristics and chronic conditions. Am J Epidemiol. 1993;137(8):845-57.         

12. Guralnik JM, Fried LP, Salive ME. Disability as a public health outcome in the aging population. Annu Rev Public Health. 1996;17:25-46. DOI:10.1146/annurev.pu.17.050196.000325        

13. Kaplan GA, Pamuk ER, Lynch JW, Cohen RD, Balfour JL. Inequality in Income and mortality in the United States: analysis of mortality and potential pathways. BMJ. 1996;312(7037):999-1003.         

14. Lee Y, Shinkai S. A comparison of correlates of self-rated health and functional disability of older persons in the Far East: Japan and Korea. Arch Gerontol Geriatr. 2003;37(1):63-76. DOI:10.1016/S0167-4943(03)00021-9        

15. Lima-Costa MF, Matos DL, Camarano AA. Evolução das desigualdades sociais em saúde entre idosos e adultos brasileiros: um estudo baseado na Pesquisa Nacional por Amostra de Domicílios (PNAD 1998, 2003). Cienc Saude Coletiva. 2006;11(4):941-50. DOI:10.1590/S1413-81232006000400016        

16. Maciel ACC, Guerra RO. Influência dos fatores biopsicossociais sobre a capacidade funcional de idosos residentes no nordestes do Brasil. Rev Bras Epidemiol. 2007;10(2):178-89. DOI:10.1590/S1415-790X2007000200006        

17. Melzer D, McWillians B, Brayne C, Johnson T, Bond J. Profile of disability in elderly people: estimates from a longitudinal population study. BMJ. 1999;318(7191):1108-11.         

18. Murtagh KN, Hubert HB. Gender differences in physical disability among an elderly cohort. Am J Public Health. 2004;94(8):1406-11. DOI:10.2105/AJPH.94.8.1406        

19. Parahyba MI, Veras R, Melzer D. Incapacidade funcional entre as mulheres idosas no Brasil. Rev Saude Publica. 2005;39(3):383-91. DOI: 10.1590/S0034-89102005000300008        

20. Pinheiro RS, Torres TZG. Uso de serviços odontológicos entre os Estados do Brasil. Cienc Saude Coletiva. 2006;11(4):999-1010. DOI:10.1590/S1413-81232006000400021        

21. Porell FW, Miltiades HB. Regional differences in functional status among the aged. Soc Sci Med. 2002;54(8):1181-98. DOI:10.1016/S0277-9536(01)00088-0        

22. Rasbash J, Browne W, Goldstein H, Yang M, Plewis I, Healy M, et al. A user's guide to MLwiN. London: Institute of Education; 2000.         

23. Rutherford RD, Chloe MK. Statistical models for causal analysis. New York: Wiley; 1993.         

24. Rosa TEC, Benício MHA, Latorre MRDO, Ramos LR. Fatores determinantes da capacidade funcional entre idosos. Rev Saude Publica. 2003;37(1):40-8. DOI:10.1590/S0034-89102003000100008        

25. Ross CE, Wu CL. Education, age, and the cumulative advantage in health. J Health Soc Behav. 1996;37(1):104-20. DOI:10.2307/2137234        



Luciana Correia Alves
Sala da Coordenação de Ensino e Pesquisa
R. Leopoldo Bulhões, 1480 - Manguinhos
21041-210 Rio de Janeiro, RJ, Brasil
E-mail: luciana.alves@ensp.fiocruz.br

Received: 2/4/2009
Approved: 12/4/2009



LC Alves was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (National Council for Scientific and Technological Development - CNPq; doctoral scholarship; Process no.: 141861/2005-3).
The authors declare that there are no conflicts of interest.
a Instituto Brasileiro de Geografia e Estatística. Pesquisa Nacional por Amostras de Domicílio 2003 - Available in CD-ROM.
b Instituto de Pesquisa Econômica Aplicada. [internet] [cited 2008 Apr 21] Available from: http://www.ipeadata.gov.br/ipeaweb.dll/ipeadata?65370046
c Instituto Brasileiro de Geografia e Estatística. Produto interno bruto dos municípios: 1999-2002 [internet]. Rio de Janeiro, 2005 (Contas nacionais, 14). [cited 2008 Apr 23] Available from: http://www.ibge.gov.br/home/estatistica/economia/pibmunicipios/2002/pibmunic2002.pdf

Faculdade de Saúde Pública da Universidade de São Paulo São Paulo - SP - Brazil
E-mail: revsp@org.usp.br