Effect of influenza on functional decline

Abstract

Objectives: To examine the relationship between influenza and activity of daily living (ADL) decline and other clinical indicators in nursing home (NH) residents.

Design: Retrospective NH-aggregated longitudinal study.

Setting: Two thousand three hundred fifty-one NHs in 122 U.S. cities from 1999 to 2005.

Participants: Long-stay (>90 days) NH residents.

Measurements: Quarterly city-level influenza mortality and state-level influenza severity. Quarterly incidence of Minimum Data Set-derived ADL decline (≥ 4 points), weight loss, new or worsening pressure ulcers (PUs), and infections. Outcome variables chosen as clinical controls were antipsychotic use, restraint use, and persistent pain.

Results: City-level influenza mortality and state-level influenza severity were associated with higher rates of large (≥ 4 points) ADL decline (mortality β = 0.20, P < .001; severity β = 0.18, P < .001), weight loss (β = 0.19, P < .001; β = 0.24, P < .001), worsening PUs (β = 0.04, P = .08; β = 0.12, P < .001), and infections (β = 0.41, P < .001; β = 0.47, P < .001) but not with restraint use, antipsychotic use, or persistent pain. NH influenza vaccination rates were weakly associated with the outcomes (e.g., β = -0.009, P = .03 for ADL decline, β = 0.008, P = .07 for infections). Compared with the summer quarter of lowest influenza activity, the results for the other quarters translate to an additional 12,284 NH residents experiencing large ADL decline annually, 15,168 experiencing significant weight loss, 6,284 new or worsening PUs, and 29,753 experiencing infections due to influenza.

Conclusion: The results suggest a substantial and potentially costly effect of influenza on NH residents. The effect of influenza vaccination on preventing further ADL decline and other clinical outcomes in NH residents should be studied further.

Figure 1

1A–1G. Quarterly Patterns of Functional Outcomes () versus Influenza City-Level Mortality () (functional outcomes rates (range 0–1) on the left vertical axis, influenza mortality (Deaths/100,000 population) on the right vertical axis) for long-stay (>90 days) nursing home residents in 122 CDC-monitored cities in the USA. The outcomes (from left to right and top to bottom) are prevalence rates of 1. Large ADL decline (>3 points in the 0–28 ADL scale); 2. Weight Loss; 3. Worsening Pressure Ulcers; 4. Infections; 5. Use of Restraints; 6. Use of Antipsychotics; 7. Persistent Pain.

Figure 2

2A–2D. Quarterly Patterns of Functional Outcomes () versus Influenza State-Level Severity () (functional outcomes rates (range 0–1) on the left vertical axis, influenza severity scales (range 1–5) on the right vertical axis). for long-stay (>90 days) nursing home residents in 122 CDC-monitored cities in the USA. The outcomes (from left to right and top to bottom) are prevalence rates of 1. Large ADL decline (>3 points in the 0–28 ADL scale); 2. Weight Loss; 3. Worsening Pressure Ulcers; 4. Infections.