SciELO - Scientific Electronic Library Online

 
vol.13 número5Estudo inédito sobre o pesquisador fisioterapeuta brasileiroInfluência das características sociodemográficas e epidemiológicas na capacidade funcional de idosos residentes em Ubá, Minas Gerais índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Serviços Personalizados

Journal

Artigo

Indicadores

Links relacionados

Compartilhar


Brazilian Journal of Physical Therapy

versão impressa ISSN 1413-3555versão On-line ISSN 1809-9246

Rev. bras. fisioter. vol.13 no.5 São Carlos set./out. 2009  Epub 13-Nov-2009

http://dx.doi.org/10.1590/S1413-35552009005000061 

YSTEMATIC REVIEW

 

Physical therapy treatment on frailty syndrome: systematic review

 

 

Paula M. M. ArantesI; Mariana A. AlencarI; Rosângela C. DiasII; João Marcos D. DiasII; Leani S. M. PereiraII

IGraduate Program in Rehabilitation Sciences, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (MG), Brazil
IIDepartment of Physical Therapy, UFMG, Belo Horizonte (MG), Brazil

Correspondence to

 

 


ABSTRACT

OBJECTIVE: To carry out a systematic review of the literature on physical therapy interventions and their effect on frail community-dwelling elders.
METHODS: Systematic review of studies published until June 2008 in the databases Medline, Embase, PEDro, SciELO, LILACS and Cochrane Library. We excluded studies with samples composed of institutionalized, hospitalized and non-frail participants, studies not aimed at treating frailty, and studies that were not specifically related to physical therapy.
RESULTS: In accordance with the exclusion criteria, out of the 152 Medline articles, only 15 were considered for analysis, out of the 71 PEDro articles only one was considered as the other ten had already been selected in Medline, and out of the 461 Embase articles only two that had not been selected in others databases were included in this study. A total of seven different types of interventions were verified: 1) muscle strengthening; 2) exercises for muscle strengthening, balance, coordination, flexibility, reaction time and aerobic training; 3) functional training; 4) physical therapy; 5) at-home physical therapy; 6) environment adaptation and prescription of assistive device; 7) water exercise. The results of some studies were contradictory even with similar interventions. The analyzed studies had different definitions for fragility, which made it difficult to compare the results.
CONCLUSION: There is little evidence of the effect of physical therapy intervention on frail community-dwelling elders; thus, it is not possible to reach a consensus or conclusion on the effectiveness of the therapeutic regimens proposed for this complex syndrome.

Key words: elderly; frail; physical therapy; rehabilitation.


 

 

Introduction

Studies on the frail elderly population are still scarce worldwide and in Brazil. However, the increase in frail elders, associated with their social and economic impact, has generated increased interest in the topic and the need to better investigate this population1. A major difficulty in studying this population is the definition of frailty. Although there is no consensus on the definition of frailty, it is widely accepted as a multifactorial, clinical syndrome characterized by a state of physiological vulnerability resulting from a decrease in energy reserves and the ability to maintain or restore homeostasis after a destabilizing event2,3. Frailty syndrome is complex and involves declines in many physiological domains, including strength and muscle mass, flexibility, balance, coordination and cardiovascular function4,5, which generate high risk of falls, functional decline, hospitalization and death6. Frailty leads to the deterioration of quality of life, caregiver overload and high health care expenses7. Thus, non-pharmacological interventions that can prevent or delay the progression of frailty are necessary3,8,9.

Exercise programs are pointed out as the best type of intervention to improve physical function3. However, despite the evidence demonstrating the beneficial effects of exercise in the elderly, there is still a limited number of studies on the effects of exercise programs on frail elders. The aim of this study was to carry out a systematic review of the literature on the effects of physical therapy interventions on frail community-dwelling elders.

 

Methods

Using the descriptors frail or frailty, older adults or elderly, rehabilitation or intervention, physical therapy or exercise therapy and the equivalents in Portuguese and Spanish, we found articles which had those key words on the title or abstract and were published until June 2008 in the electronic databases MEDLINE, Embase, PEDro, SciELO, LILACS and Cochrane Library, in English, Portuguese and Spanish. We also carried out a manual search in the dissertation and thesis libraries at Universidade Federal de Minas Gerais, Universidade de São Paulo, Universidade Federal do Rio de Janeiro, Universidade Federal do Rio Grande do Sul, Universidade de Campinas and Universidade Federal de São Carlos, which are the main centers for research in this area and allow this search. Additionally, we consulted experts in the field to investigate the possibility of other references that were not part of the databases consulted.

The inclusion criterion was that the study should be a clinical trial, controlled clinical trial or randomized clinical trial. Studies were excluded if the sample was composed not only of frail elders, the goal of intervention was not frailty, the intervention was not specifically a physical therapy intervention or if there were multiple interventions. Studies that presented only preliminary data or were conducted with institutionalized or hospitalized elders were also excluded. The articles were chosen by two independent reviewers, according to the inclusion criteria, the title and the abstract. In case of disagreement, the reviewers read the full article, discussed it, and passed it on to a third reviewer.

The methodology of the selected studies was evaluated by the PEDro scale10,11, which is widely used in the field of rehabilitation. The scale has a total score of 10 points10,11 and evaluates the methodological quality of experimental studies. Scores >5 are considered of high quality12. The studies were classified by two reviewers independently. The Kappa Index was used to evaluate the level of agreement between reviewers in relation to the PEDro scores. For the final quality classification, the discrepant items were reviewed and discussed until consensus on the score was reached11.

 

Results

In the search performed in June 2008, 152 studies were found in the MEDLINE database, only 15 of which met all the inclusion criteria; 71 were found in the PEDro, 11 of which were selected. Of these 11 articles, 10 had already been selected in MEDLINE. In Embase database, 461 articles were found, and only two articles from this database had not been selected in other database searches and met the inclusion criteria. No other articles were found in the remaining databases. The characteristics of the selected articles in terms of intervention, outcomes and results are presented in Table 1. There was great variability in the type of intervention used and the outcomes analyzed, with a total of seven different types of intervention. Moreover, the criteria used to define the frail elders varied considerably from study to study (Table 2).

 

 

Most of the articles (56%) had scores >5 on the PEDro scale (EP), and thus were considered of high quality12 (Table 2). Regarding this classification, the evaluators showed good agreement (Kappa = 0.829, p<0.001).

Muscle strengthening

Five studies evaluated the effects of strength training in frailty elders1,5,13-15. Two found no significant differences both for quadriceps muscle strength5 and lower and upper limb muscle strength1. The three remaining studies showed a significant increase in muscle strength. In the study conducted by Sullivan et al.13, high- and low-resistance isotonic exercises increased the leg and arm muscle strength of frail elders, particularly in the high-resistance training group. Chandler et al.14 found a gain in strength of 10 to 16% after a low to moderate exercise program. LaStayo et al.15 found an increase in the cross-sectional area and strength of the lower limbs after eccentric strength training on a cycle ergometer.

All articles also evaluated the effect of strength training on functional mobility, but only two studies1,15 found a significant improvement in the time taken to perform the Timed Up and Go (TUG) test and the 10-meter walk1 and in stair descending ability15. The remaining studies5,13 did not find a significant difference for measures of functional capacity. Three studies evaluated balance1,5,15 with conflicting results. Ota et al.1 found an improvement in the Functional Reach test after a strength training program for upper and lower limb muscles. LaStayo et al.15 found an improved Berg Balance Scale score in the group that trained on the cycle ergometer. In contrast, Latham et al.5 found no benefits of quadriceps strengthening in the Berg Balance Scale score.

Exercises for muscle strengthening, balance, coordination, flexibility, reaction time and aerobic training

Three studies evaluated the impact of a multiple-intervention program, including muscle strengthening, balance, coordination, flexibility, reaction time and aerobic training on different outcomes when treating a frail elder4,16,17. Peak O2 uptake (VO2 peak) was a common outcome in the studies by Ehsani et al.16 and Binder et al.4, and both found a significant increase of 14%. Ehsani et al.16 also evaluated the impact of this protocol on cardiac output and left ventricular stroke work with significant increases in the experimental group. Regarding the other outcomes evaluated by Binder et al.4, the intervention program produced significant improvement in muscle strength, balance, self-perceived health and function (self-report and performance). Worm et al.17 found significant improvement in the performance and self-report of physical function in gait (speed and number of steps) and muscle strength, but there was no statistical analysis of VO2 max.

Functional training

Five studies evaluated the effects of an exercise program focused on functional skills training (reach, stand up from chair, throw, etc.) necessary to perform daily activities in the frail community-dwelling elders18-22. Four of these studies used the same protocol of intervention, but evaluated different outcomes. Chin et al.18 evaluated the effect of intervention on the subjective wellbeing, self-reported health and social contact and found no significant changes. However, Helbostad, Sletvold and Moe-Nilssen22 found significantly greater improvement than the control group in the mental health index and emotional aspects of quality of life. The results of that same study, however, did not show significant effects of functional training on gait speed22. In another study, there was a significant improvement in the functional capacity of the elders in the intervention group19. The activities that had significant changes were standing up from chair, reaching toes and gait speed. Regarding self-reported functional capacity, there was no significant change. Regarding body composition, there was an increase in lean body mass in the elders who underwent functional training20,21. There was no significant change in body mass, waist and hip circumference.

Physical therapy (balance exercises, coordination, flexibility, strengthening and reaction time)

We found only one study that evaluated the effects of this type of intervention on frail community-dwelling elders23. It showed significant improvement in muscle strength, flexibility, balance, coordination, cadence and function in the intervention group. There were no significant differences for reaction time variables, sensitivity and gait variables. The control group, which performed the exercises to gain range of motion at home, only showed significant improvement in flexibility.

At-home Physical Therapy (environment adaptation + prescription of assistive devices + exercise)

Two studies evaluated the impact of a personalized physical therapy program based on the evaluation of the elder and his home environment. The program was held in the homes of elderly and supervised by a physical therapist7,24. The outcomes vary between the two studies. In the first study24, most of the elders did not advance beyond the initial level of resistance in the strengthening exercises. There was no statistical analysis of the data, which hampers its generalization. The authors also reported that the program was safe, because the adverse events were not more common in the experimental group. In the other study7, the intervention group had a significant reduction in disability compared to the group that received educational lectures. The benefits were greater in the moderate frailty group compared to the severe group.

Environment adaptation + prescription of assistive device

One study evaluated the effectiveness of environmental intervention combined with the prescription of assistive devices, when necessary, in function, pain and health care cost of frail elders25. After 18 months of intervention, both groups showed a decline in function evaluated by the Functional Independence Measure (FIM) questionnaire, however this decline was greater in the control group. Thus, the intervention was not able to prevent functional decline, but it did slow it down. Only the control group showed an increase in pain. The comparison of health care cost found no difference in total expenses, however the control group had greater expenses with institutionalization.

Water exercise

Only one study evaluated the effect of water exercise on frail elders26. The study investigated the effect of once-weekly and twice-weekly intervention over a six-month period. In the quality of life outcome, there was a significant increase in the physical and mental components of the SF-36 questionnaire at three and six months of exercise, compared with the pre-intervention assessment. There were no differences in the control group. There was also a significant difference in the FIM score between the pre-intervention and six-month assessments for both intervention groups and between the pre-intervention and three-month assessments only for the twice-weekly group. No differences were found in the control group26.

 

Discussion

This systematic review shows the lack of studies on intervention in frail community-dwelling elders, despite the great importance of the topic. This lack may be related to the great challenges of working with this population, such as the lack of standardized criteria for the definition of frailty, ethical issues and high dropout and mortality rates, which hamper the performance of these studies8. One problem that complicates the evaluation of interventions in frail elders is the fact that the analyzed studies use different concepts to define frail elders. The definitions ranged from functional changes and need for help to the combination of multiple characteristics (Table 2). These limitations made it impossible to generalize the results and to compare these studies with other studies.

Ferrucci et al.8 attempted to solve this problem by proposing the use of a consensus for studies on interventions in frail elders. These authors recommend the evaluation of the mobility, nutrition and body composition domains. This recommendation is based on the fact that the frailty syndrome is multisystemic and multifactorial in nature3,6. Although considered synonymous by many authors and health professionals, disability and frailty are separate entities and can occur in isolation in the elderly. This distinction is well demonstrated in the study by Fried et al.2, in which 72.8% of frail elders had no disability and 72% of disabled elders were not frail.

This multisystemic character of frailty and its different definitions may also have influenced the great variety of outcomes found in the studies. This heterogeneity of outcomes further complicates the verification of evidence in the rehabilitation of frail elders. However, some studies share similar outcomes, the most common being functional capacity evaluated by self-reported performance or by physical performance measures1,4,5,7,13-15,17-20,22-26. This fact may be related to the increased risk of functional decline presented by this population and to the serious repercussions of disability6,8,9.

The forms of intervention differed greatly between studies, even when the outcome was the same. Some studies attempted a more pragmatic therapeutic approach with protocols varying according to the individual evaluation of each elder24, some with exercises that could be performed at home5,14, others with specific exercises to be performed in clinical settings1,13 and another with a combination of exercise at home and in the clinical setting17.

Regarding the muscle strengthening programs, the study results were contradictory in several evaluated outcomes. Differences in treatment parameters do not seem to justify the significant differences in results, as most of the parameters were different between studies that found the same result and had similarities with studies that had different results. In the strengthening studies, the intervention period ranged from 105,14 to 12 weeks1,13, two1 to three times a week5,13-15, and the number of repetitions was three sets of eight5,13 or ten1 or two sets of ten14. All studies adopted a systematic load adjustment and differed in muscle strength training equipment, with the exception of one study that did not describe how the load adjustments were made or the number of sets17. Caution is needed when interpreting the effects of strengthening in frailty elders, since the studies have issues with regard to quality1,15, methodological structure5,13 and definition of frailty1,5,13-15,17.

As described above, two studies evaluated the impact of a three-stage program including physical therapy, muscle strengthening and aerobic training4,16 to treat frail octogenarians. The two studies were developed at the same study center and with the same researchers. The sample of the study by Ehsani et al.16 consisted of elders who took part in the study by Binder et al.4, and the protocol was the same. However, the study by Ehsani et al.16 focused on aspects related to cardiorespiratory function, while Binder et al.4 also evaluated aerobic capacity and other aspects related to functional capacity, muscle function, balance and self-related health. The two studies found positive effects of this protocol on the evaluated variables, showing that even a frail octogenarian is capable of making beneficial biological adaptations. Worm et al.17, who also used multiple interventions, found benefits of this intervention in frail elders, but did not give a clear definition of frail elder.

There is little evidence of the benefits of functional training in frail elders. Although five articles were found on the effects of functional training, four of them belonged to the same study, but considering different outcomes18-21. In fact, the articles were simply divided according to the outcomes. Thus, despite the benefits of the program to functional capacity, increase in lean body mass and quality of life, the results are still scarce for this type of intervention.

Studies on the effectiveness of physical therapy interventions and environment adaptation plus prescription of assistive devices were found in the literature7,23-25. One advantage of these interventions is that they are similar to the approach taken by the physical therapist in clinical practice, with implementation of a multifactorial program. The study by Brown et al.23 evaluated the effect of a low-intensity physical therapy program including balance, coordination, flexibility, strengthening and reaction time exercises on the treatment of frail elders. The authors found significant improvements in muscle strength, flexibility, balance, coordination, cadence and function after six months of intervention, three times a week. They concluded that this may be an effective alternative for elders who cannot follow more rigorous programs. However they also concluded that, despite the improvement in physical function, frailty was not eliminated, thus enhancing the importance of prevention.

The authors who evaluated the effectiveness of environment adaptation and prescription of assistive devices and of these approaches combined with exercise came to the important conclusion that these interventions were able to reduce functional decline, but not avoid it7,25. Both studies followed up the elders for a period of 12 and 18 months, and one of them showed that the benefits only appeared after six months of intervention. Thus, the duration of interventions in frail elders in order to improve the function should be chosen with caution. Furthermore, the level of frailty must be taken into account, because when the elders were divided into moderate and severe, those with severe frailty did not benefit from the intervention. However, one should be cautious in interpreting these data due to the difficulty of categorizing the level of frailty and the small number of studies evaluating this issue.

The only study that evaluated the benefits of water exercise was the study by Sato et al.26. They found an improvement in quality of life and function in elders who they considered frail. They also found that the frequency of practice also influences the speed of improvement. The researchers considered frail the elders who had five functional limitations and adopted more stringent selection criteria. Therefore, depending on the definition of frailty used by a professional, the water environment can place the elders at risk of complications.

A major problem verified in this review was related to the quality of the available studies. Some important methodological limitations were found, and some studies show low methodological quality in the PEDro scale evaluation1,4,15,20,23,24, which complicates the interpretation of results. In two studies, the elders were not randomly assigned to groups5,15. In many of them, the examiners were not blinded1,4,7,15-21,23-25, there was no analysis by intention-to-treat1,4,7,14,16-21,23-25, and only one study22 mentioned that the sample size was calculated. This issue becomes extremely important in studies with high dropout and mortality rates, as it is the case of the analyzed studies. It is recommended that sample losses be limited to 20% and included in the sample calculation, and that analyses be run by intention-to-treat8. The studies did not follow these recommendations. Regarding statistical power, only one article5 made this calculation, but it is not possible to say whether the lack of significant improvement after intervention in some studies was due to a lack of efficacy of the technique or due to insufficient sample size.

Another difficulty encountered by the present study was the large number of interventions found in the literature, with a small number of publications for each type of intervention. This certainly limits the conclusions. Future studies should evaluate each specific type of intervention, considering that there is a clear need of intervention studies on the subject. Moreover, it is important that future studies use appropriate criteria for the definition of frailty and make them clear in the text.

 

Conclusion

There is little evidence of the effects of interventions or prevention on frail community-dwelling elders. The diversity of criteria used to define the frail elder makes it difficult to conduct and to compare studies. Due to the small number of studies found, it was not possible to reach a consensus regarding the effectiveness of interventions. Some authors seem to agree that, despite the significant gains in strength, balance and functional capacity, the intervention were not able to reverse or prevent the progression of frailty.

 

References

1. Ota A, Yasuda N, Horikawa S, Fujimura T, Ohara H. Differential effects of power rehabilitation on physical performance and higher-level functional capacity among community-dwelling older adults with a slight degree of frailty. J Epidemiol. 2007;17(2):61-7.         [ Links ]

2. Fried LP, Ferrucci L, Darer J, Williamson JD, Anderson G. Untangling the concepts of disability, frailty, and comorbidity: implications for improved targeting and care. J Gerontol A Biol Med Sci. 2004;59(3):255-63.         [ Links ]

3. Walston J, Hadley EC, Ferrucci L, Guralnik JM, Newman AB, Studenski SA, et al. Research agenda for frailty in older adults: toward a better understanding of physiology and etiology: summary from the american geriatrics society/national institute on aging research conference on frailty in older adults. J Am Geriatr Soc. 2006;54(6):991-1001.         [ Links ]

4. Binder EF, Schechtman KB, Ehsani AA, Steger-May K, Brown M, Sinacore DR, et al. Effects of exercise training on frailty in community-dwelling older adults: results of a randomized, controlled trial. J Am Geriatr Soc. 2002;50(12):1921-8.         [ Links ]

5. Latham NK, Anderson CS, Lee A, Bennett DA, Moseley A, Cameron ID, et al. A randomized, controlled trial of quadriceps resistance exercise and vitamin D in frail older people: the Frailty Interventions Trial in Elderly Subjects (FITNESS). J Am Geriatr Soc. 2003;51(3):291-9.         [ Links ]

6. Fried LP, Tangen C, Walston J, Newman A, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Med Sci. 2001;56(3): M146-56.         [ Links ]

7. Gill TM, Baker DI, Gottschalk M, Peduzzi PN, Allore H, Byers A. A program to prevent functional decline in physically frail, elderly persons who live at home. N Engl J Med. 2002;347(14):1068-74.         [ Links ]

8. Ferrucci L, Guralnik JM, Studenski S, Fried LP, Cutler GB Jr, Walston JD, et al. Designing randomized, controlled trials aimed at preventing or delaying functional decline and disability in frail, older persons: a consensus report. J Am Geriatr Soc. 2004;52(4):625-34.         [ Links ]

9. Speechley M, Tinetti M. Falls and injuries in frail and vigorous community elderly persons. J Am Geriatr Soc. 1991;39(1):46-52.         [ Links ]

10. Maher CG, Sherrington C, Herbert RD, Moseley AM, Elkins M. Reliability of the PEDro scale for rating quality of randomized controlled trials. Phys Ther. 2003;83(8):713-21.         [ Links ]

11. Sampaio RF, Mancini MC. Estudos de revisão sistemática: um guia para síntese criteriosa da evidência científica. Rev Bras Fisioter. 2007;11(1):83-9.         [ Links ]

12. Moseley AM, Herbert RD, Sherrington C, Maher CG. Evidence for physiotherapy practice: a survey of the physiotherapy evidence database (PEDro). Austr J Physiother. 2002;48(1):43-9.         [ Links ]

13. Sullivan DH, Roberson PK, Johnson LE, Bishara O, Evans WJ, Smith ES, et al. Effects of muscle strength training and testosterone in frail elderly males. Med Sci Sports Exerc. 2005;37(10):1664-72        [ Links ]

14. Chandler JM, Duncan PW, Kochersberger G, Studenski S. Is lower extremity strength gain associated with improvement in physical performance and disability in frail, community-dwelling elders? Arch Phys Med Rehabil. 1998;79(1):24-30.         [ Links ]

15. LaStayo PC, Ewy GA, Pierotti DD, Johns RK, Lindstedt S. The positive effects of negative work: increased muscle strength and decreased fall risk in a frail elderly population. J Gerontol A Biol Sci Med. 2003;58(5):419-24.         [ Links ]

16. Ehsani AA, Spina RJ, Peterson LR, Rinder MR, Glover KL, Villareal DT, et al. Attenuation of cardiovascular adaptations to exercise in frail octogenarians. J Appl Physiol. 2003;95(5):1781-8.         [ Links ]

17. Worm CH, Vad E, Puggaard L, Stovring H, Lauritsen J, Kragstrup J. Effects of a multicomponent exercise program on functional ability in community-dwelling, frail older adults. J Aging Phys Activ. 2001;9(4):414-24.         [ Links ]

18. Chin A Paw MJ, de Jong N, Schouten EG, van Staveren WA, Kok FJ. Physical exercise or micronutrient supplementation for the wellbeing of the frail elderly? A randomized controlled trial. Br J Sports Méd. 2002;36(2):126-31.         [ Links ]

19. Chin A Paw MJ, de Jong N, Schouten EG, Hiddink GJ, Kok FJ. Physical exercise and/or enriched foods for functional improvement in frail, independently living elderly: a randomized controlled trial. Arch Phys Med Rehabil. 2001;82(6):811-7.         [ Links ]

20. de Jong N, Chin A Paw MJ, de Graaf C, van Staveren WA. Effect of dietary supplements and physical exercise on sensory perception, appetite, dietary intake and body weight in frail elderly subjects. Br J Nutr. 2000;83(6): 605-13.         [ Links ]

21. de Jong N, Chin A Paw MJ, de Groot LC, Hiddink GJ, van Staveren WA. Dietary supplements and physical exercise affecting bone and body composition in frail elderly persons. Am J Public Health. 2000;90(6):947-54.         [ Links ]

22. Helbostad JL, Sletvold O, Moe-Nilssen R. Home training with and without additional group training in physically frail old people living at home: effect on health-related quality of life and ambulation. Clin Rehabil. 2004;18(5):498-508.         [ Links ]

23. Brown M, Sinacore DR, Ehsani AA, Binder EF, Holloszy JO, Kohrt WM. Low-intensity exercise as a modifier of physical frailty in older adults. Arch Phys Med Rehabil. 2000;81(7):960-5.         [ Links ]

24. Gill TM, Baker DI, Gottschalk M, Gahbauer EA, Charpentier PA, de Regt PT, et al. A prehabilitation program for physically frail community-living older persons. Arch Phys Med Rehabil. 2003;84(3):394-404.         [ Links ]

25. Mann WC, Ottenbacher KJ, Fraas L, Tomita M, Granger CV. Effectiveness of assistive technology and environmental interventions in maintaining independence and reducing home care costs for the frail elderly. A randomized controlled trial. Arch Fam Med. 1999;8(3):210-7.         [ Links ]

26. Sato D, Kaneda K, Wakabayashi H, Nomura T. The water exercise improves health-related quality of life of frail elderly people at day service facility. Qual Life Res. 2007;16(10):1577-85.         [ Links ]

 

 

Correspondence to:
Paula Maria Machado Arantes
Rua Muzambinho, 159 - apto 401, Anchieta
CEP 30310-280, Belo Horizonte (MG), Brazil
e-mail: paulamma@gmail.com

Received: 17/11/2008
Revised: 30/04/2009
Accepted: 06/08/2009

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons