Preventing disability and death in old age

Andreas Stucka and John C Beckb

a Zieglerspital, Department of Geriatrics and Rehabilitation, 3001 Bern, Switzerland. Email: andreas.stuck{at}spitalbern.ch
b UCLA School of Medicine, Los Angeles, USA.

Sir—The Spotlight section of the Journal1 raised questions with regard to a randomized controlled study of preventive home visits conducted in Berne, Switzerland.2 The first, whether ‘area effects accounted for differences in outcomes’ can be answered with ‘no’ for all main outcomes. Main outcomes were analysed on an intention-to-treat basis for all project areas combined, and significant favourable effects were found for people at low baseline risk. For persons at high baseline risk, the analyses showed a significantly higher number of nursing home admissions in subjects of the intervention group as compared to controls.

There was an unfavourable, but statistically non-significant trend towards a higher 3 year mortality rate in subjects of the intervention group as compared to controls among subjects at high risk (P = 0.10, based on adjusted multivariate logistic regression analysis). Sensitivity analysis based on a survival analysis without adjustment for baseline factors revealed a P-value of 0.06. We also collected survival data for 4 additional months and conducted a 40-month follow-up analysis. At 40 months, the difference in mortality between intervention and control groups was non-significant, with P-values of P = 0.20 for adjusted logistic regression analysis, and P = 0.16 for unadjusted survival analysis. Thus, the Spotlight hypothesis that the intervention killed high-risk patients due to delay in seeking appropriate specialist care is unwarranted since the implementation of the intervention did not interfere with the delivery of specialist care and since mortality differences were not statistically significant.

The Spotlight also addressed potential confounding in subgroup analyses of this study. We reported subgroup analyses that were based on the observation that one nurse's professional performance appeared to differ from that of the other two nurses. Study conclusion analyses revealed that one nurse detected significantly fewer problems in older people as compared to the other nurses, despite comparable population characteristics between nurses. We found no favourable intervention effects among people at low baseline risk visited by this nurse; and among people at high baseline risk visited by this nurse, there was a statistically significant higher number of nursing home admissions as compared to controls. In contrast, for people at low baseline risk visited by the other nurses, effects were favourable, and for persons at high baseline risk visited by the other nurses, there was no increase of nursing home admissions. It is very unlikely that these differences in outcomes between nurses might be explained by confounding with area effects. Nurse performance differences were major, but socio-economic and health status differences between areas were minor and adjustment of analyses for these baseline factors did not affect the results.

The Spotlight also addressed why doctors refuse to accept satisfaction as a valid outcome for chronic conditions, yet continue to measure it. This study revealed that more than 90% of older people responded that they were satisfied with the visits. We collected this information because we think it is an important factor determining future programme implementation. However, the finding that subjects at high baseline risk were as satisfied with the project as subjects with low baseline risk emphasizes that satisfaction alone does not differentiate between cost-effective and non cost-effective programmes.

We cannot answer the question as to whether only particular or all instrumental activities of daily living were improved by the project, due to the limited power of the study of conducting these analyses. The statistically significant effects on basic activities of daily living observed among subjects visited by the nurses with a high level of professional competence as compared to control subjects suggests that in-home prevention has favourable effects on both instrumental and basis activities of daily living. The analyses conducted in this study suggested that this was achieved by an improvement of mobility, but not of cognitive function.

In summary, (1) this study suggests that in contrast to currently held beliefs, low-risk older people might benefit more from in-home prevention as compared to high-risk people, and (2) in interventions of this type, professional competence of the intervention personnel is likely to be a key factor responsible for programme effects which can be monitored by measuring the number and type of problems identified by the home visitor, as well as the recommendations and adherence to recommendations for tracer conditions (such as vaccination rate, appropriateness of medication use, patients' physical activity, etc.) and by experts conducting case discussions or observing home visits in selected older people.

References

1 Spotlight: Preventing disability and death in old age—it ain't what you do, it's how you do it. Int J Epidemiol 2000;29:607.[Free Full Text]

2 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]





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