Relationship between peak expiratory flow and incidence of frailty, deaths and falls among nursing home residents: Results of the SENIOR cohort
Introduction
Frailty is a major public health issue in older people (Buckinx, Rolland et al., 2015). This geriatric syndrome is defined as a state of increased vulnerability to stressors accompanied by a loss of reserves of different physiological systems (Fried et al., 2001; Rockwood, 2016). Screening and diagnosing frailty in the older population is important to prevent its related negative consequences, such as mortality, falls and loss of autonomy (Leng, Chen, & Mao, 2014). Practical indicators are then used to identify frail people or subjects at risk of becoming frail. Because frailty is associated with a decrease in muscle strength and physical capacity (Tabue-Teguo et al., 2018), their assessment seems to be highly relevant in clinical practice (Furtado, Patrício, Loureiro, Teixeira, & Ferreira, 2017; Xie et al., 2017). For some muscle and physical capacity assessments, different tools are needed, limiting their use in particular settings, such as nursing homes.
Lung function and respiratory muscle strength are known to decrease with age and are associated with reduced physical capacity, occurrence of death and health status (Vaz Fragoso, Gahbauer, Van Ness, Concato, & Gill, 2008) and consequently could be interesting markers of frailty and its consequences (Marengoni et al., 2018). The gold standard technique to evaluate lung function is spirometry (Miller et al., 2005), but it is not applicable in the specific setting of nursing homes since it necessitates complex training and specific equipment (Bellia et al., 2000). Peak expiratory flow (PEF), defined as the maximum instantaneous flow achieved during a forced expiration maneuver from maximal lung inflation (Quanjer, Lebowitz, Gregg, Miller, & Pedersen, 1997), is very easy to obtain from non-trained individuals and can be a practical lung function measurement to obtain from older people in large studies.
Vaz Fragoso et al. found that PEF was a risk assessment tool for frailty, especially for exhaustion and inactivity (Vaz Fragoso, Gahbauer, Van Hess, Gill, & Yu, 2009). Other studies established cross-sectional and longitudinal associations between respiratory function and frailty in community-dwelling older people using spirometry parameters such as FEV1 (forced expiratory volume) but not taking into account the PEF (Pegorari, Ruas, & Patrizzi, 2013; Vaz Fragoso, Enright, McAvay, Van Ness, & Gill, 2012; Weiss, Hoenig, Varadhan, Simonsick, & Fried, 2010). Low PEF in older people can predict health outcomes such as mortality and cognitive decline (Albert et al., 1995). Little is known about the relationship between PEF and falls (Gale, Cooper, Westbury, & Dennison, 2016). However, no studies were performed in nursing homes.
Moreover, studies of peak flow meter reproducibility in older people or nursing home populations are lacking in the literature. There are also no reference values for very old populations in nursing homes. Studies of the specific population of nursing home residents are scarce, and data are lacking about PEF. The objectives of the present study were to evaluate the reproducibility of the PEF, to calculate normative values of PEF and to investigate, for the very first time, the relationship between low PEF and the incidence of frailty, deaths and falls among nursing home residents.
Section snippets
Population and study design
The present study was performed using the first year of follow-up of the SENIOR (Sample of Elderly Nursing home Individuals: an Observational Research) cohort. The SENIOR cohort is a longitudinal ongoing study conducted in 28 nursing homes in the Liege area (Belgium). This cohort of 662 subjects started in 2013, and all participants were invited every year to participate in the follow-up examination. Anamnestic, sociodemographic and clinical data were collected through individual face-to-face
Study population
At baseline, complete data for PEF were available for 646 subjects of the SENIOR cohort (Fig. 1). There were 662 subjects at baseline in the SENIOR cohort, but 16 subjects had missing data for PEF assessment. Longitudinal analyses could be performed on 332 subjects who had both frailty assessments after 1 year of follow-up and PEF assessment at baseline. Mortality and refusals to participate reduced our sample after 1 year of follow-up. The analyses of 1-year mortality and falls were carried
Discussion
The main findings of this study suggest that the percentage of theoretical PEF measured by a peak flow meter is not associated with the incidence of frailty, mortality or falls after 1 year of follow-up after adjustment for confounding variables. These results indicate that this measurement adds no more information as compared to the SPPB test. In the meantime, PEF is a very easy measurement with no need for extensive training. Peak flow meter is a portable device that is noninvasive,
Conclusion
In conclusion, in a sample of nursing home residents, the percentage of the theoretical PEF value, calculated as a function of a predictive equation, is not associated with the incidence of frailty, deaths or falls. However, PEF could be an interesting and practical alternative to collect in the absence of physical tests such as the SPPB test.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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