Commentary: Disentangling the black box of disability prevention in older people

Andreas E Stuck

Department of Geriatrics and Rehabilitation, Spital Bern Ziegler, Morillonstr. 75, CH-3001 Bern, Switzerland. E-mail: andreas.stuck{at}spitalbern.ch

Demographic changes and expected increasing numbers of disabled older people are key challenges for medical and social care systems of this century. Thus, research on the prevention of disability is a high societal priority. Recently, this research received increased attention because of a major disagreement on the effectiveness of preventive programmes for older people.1 In the current debate, the findings of the study by Garcia-Peña et al.2 are timely. Their carefully conducted randomized controlled study showed favourable effects of a preventive home visitation programme among older hypertensive people in Mexico.

This is a randomized study of disability prevention in an older population that was conducted in subjects with a predominantly low socioeconomic status (SES). Most previous studies of preventive care in older people were conducted in more affluent areas or in subjects with a higher SES. Also, since subjects with a lower SES are more likely to refuse to participate in research studies as compared to subjects with a higher SES,3 subjects with a low SES were often underrepresented in earlier studies of preventive care among older people. This uncertainty about effects of preventive programmes in subjects with low income or in subjects with a low level of education is of concern because income and education are key factors associated with disability among older people.4 For example, the recent observation of a rapidly declining prevalence of disability among the black and non-black US population was explained by a coincident rise of educational level in these populations.5 There is also empirical evidence from epidemiological studies demonstrating that the level of functional impairment associated with chronic disease is strongly influenced by the older person's SES.6 This is likely explained by the relationship between SES and factors such as access to health care; quality of health care received; adherence with preventive or therapeutic recommendations; or individual coping with chronic disease. Garcia-Peña et al.2 demonstrate that a preventive interven-tion can improve health risk among a group of subjects with low SES.

This study adds to the disentangling of the black box of disability prevention in older people. Garcia-Peña et al. focused on control of hypertension, one of the multiple potential risk factors for disability among older pepole. A recent meta-analysis revealed that absolute benefit of hypertension control is larger in subjects aged >=70 as compared to younger people.7 Other potentially modifiable risk factors for functional status decline among older people include depressive symptoms, hazardous alcohol consumption, impaired cognition, falls, sensory impairment, smoking and multiple other factors.3 Garcia-Peña et al. designed a complex intervention addressing factors associated with hypertension, including physical activity, nutrition, and medication management. Specially trained nurses conducted home visits every month or more frequently if needed and emphasized pharmacological and non-pharmacological interventions. Outcomes suggested that favourable intervention effects on blood pressure were probably related to favourable effects on the level of physical activity, on sodium intake, and on the use of antihypertensives agents. These findings add to the evidence that effective preventive programmes need to have a high level of intensity and professional quality and are not compatible with home visits conducted by inexpensive volunteers having mainly social contacts with older people.

The authors calculated that this programme would result in additional costs of US$32 per person receiving the intervention and question whether these costs are acceptable for achieving improved control of hypertension. Given the lack of more comprehensive outcome and cost data, the authors could not present a more complete cost effectiveness analysis. This is relevant because preventive programmes might necessitate an initial investment, with savings occurring only after a period of time. In fact, a recent study found that preventive home visits resulted in additional costs in the first year of follow-up, but resulted in overall net savings in the third year of follow-up because intervention subjects were less dependent and were admitted less frequently to nursing homes as compared to controls at the 3-year follow-up.8

Do the results of this study justify a widespread dissemination of this type of programme in other regions? The findings of this study might contribute to the development of a preventive programme for older people, but many questions remain to be answered. For example, one might question whether this programme could be combined with an intervention directed towards primary care physicians, increasing physicians' prescription patterns of antihypertensive agents among older people. A key question is whether the favourable effects of this intervention would persist if it was introduced into regular health care. Therefore, more information would be needed on how the nurses should be trained, and what criteria should be used to judge the quality of the intervention. A recent study found that performance among health nurses can vary substantially and influence whether or not a preventive care programme yields favourable effects.8 Finally, given the multiple and often interacting risk factors for disability among older people, the optimal method of prevention might be to design multidimensional preventive programmes that address the multiple risk factors for disability in older people. This approach could be based on the principle of comprehensive geriatric assessment.9 Such multidimensional programmes include interventions to modify risk factors for disability and also attempt to improve the use of preventive care including immunization, cancer screening, and cardiovascular risk modification. As shown by Garcia-Peña et al., it is likely that subjects of all socioeconomic classes could benefit from such interventions if programmes were developed that contain the ingredients required for effective disability prevention.

References

1 Van Haastregt JCM, Diederiks JPM, van Rossum et al. Effects of preventive home visits to elderly people living in the community: systematic review. Br Med J 2000;320:754–58.[Abstract/Free Full Text]

2 Garcia-Peña C, Thorogood M, Armstrong B, Reyes-Frausto S, Muñoz O. Pragmatic randomized trial of home visits by a nurse to elderly people with hypertension in Mexico. Int J Epidemiol 2001;30:1485–91.[Abstract/Free Full Text]

3 Norton MC, Breitner JCS, Welsh KA, Wyse BW. Characteristics of nonresponders in a community survey of the elderly. J Am Geriatr Soc 1994;42:1252–56.[ISI][Medline]

4 Stuck AE, Walthert J, Nikolaus T, Büla CJ, Hohmann C, Beck JC. Risk factors for functional status decline in community-dwelling elderly people: a systematic literature review. Soc Sci Med 1999;48:445–69.[ISI][Medline]

5 Manton KG, XiLiang G. Changes in the prevalence of chronic disability in the United States black and nonblack population above age 65 from 1982 to 1999. Proc Natl Acad Sci USA 2001;98:6354–59.[Abstract/Free Full Text]

6 Kington RS, Smith JP. Socioeconomic status and racial and ethnic differences in functional status associated with chronic diseases. Am J Public Health 1997;87:805–10.[Abstract]

7 Staessen JA, Gasowski J, Wang JG et al. Review of untreated and treated isolated systolic hypertension in the elderly: meta-analysis of outcome trials. Lancet 2000;355:865–72.[ISI][Medline]

8 Stuck AE, Minder CE, Peter-Wüest I et al. A randomized trial of in-home visits for disability prevention in community-dwelling older people at low and at high risk for nursing home admission. Arch Intern Med 2000;160:977–86.[Abstract/Free Full Text]

9 Stuck AE, Siu AL, Wieland GD, Adams J, Rubenstein LZ. Comprehensive geriatric assessment: a meta-analysis of controlled trials. Lancet 1993;342:1032–36.[ISI][Medline]





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