Ageing and COPD affect different domains of nutritional status: the ECCE study

RESULTS

Anthropometric and functional characteristic of the sample are summarised in table 1. The mean±sd age of enrolled patients was 75.0±5.9 yrs and the mean FEV₁ was 54.7±18.3% pred. Distribution of the sample by stage was as follows: 41 (8.9%) patients in stage I, 202 (43.9%) in stage II, 133 (28.9%) stage III and 61 (13.3%) stage IV; GOLD stage was undetermined in 23 (5%) patients, due to lack of acceptable spirometry.

DISCUSSION

The main finding of this study is that COPD severity and ageing are significantly, although weakly, correlated with different aspects of the nutritional status: disease severity correlated with body composition and body functionality, whereas ageing did so mainly with decreased body functionality. While BMI remains a primary index of malnutrition and disease severity, the MNA questionnaire allows a valuable insight into complexity of components of nutritional status and may provide useful clues for treatment strategies. In fact, our results suggest that prevention and treatment of body functionality deterioration might be the main objective of nutritional interventions, whatever their effects on body composition.

Our findings confirm and extend previous observations by other authors. First, it has been demonstrated that the prevalence of underweight increases with severity of COPD [12] and that fat-free mass decreases in advanced GOLD stages [19]. Furthermore, both gold standard and surrogate parameters of body composition, such as low fat-free mass [4], mid-thigh muscle cross-sectional area [11] and mid-arm muscle area [20], are better predictors of mortality than BMI. Secondly, our study demonstrates that energy intake is not correlated with disease severity. This is consistent with data from a systematic review, which indicated that nutritional support has no significant effect on anthropometric measures, lung function or exercise capacity in patients with stable COPD [21]. Furthermore, recent data [22] demonstrated that moderate-to-severe COPD patients report an adequate intake of main foods and macro- and micronutrients. However, other authors found that dietary counselling and higher caloric intake resulted in weight gain and improvement in outcome in COPD outpatients at risk of malnutrition [23].

Body composition score did not correlate with age. However, the sample of the present study only included patients aged ≥65 yrs. This narrowed range may explain this lack of expected correlation. Indeed, muscle mass loss is a progressive component of ageing, exacerbated by limited physical activity and not linked to age-associated diseases [24]. Bioelectrical impedance analysis demonstrates a clear trend toward a reduction of lean mass with age [25]. In addition, a longitudinal study confirmed a significant decrease in fat-free mass and body water in both sexes from age 75 to 80 yrs, even in the absence of significant body weight changes [26].

Data in the literature about “body functionality” in COPD patients are sparse. The most considered body functionality indices are autonomy in activities of daily life, and the number and type of current pathologies that may influence malnutrition [9]. The present study demonstrated that this component of the nutritional status was correlated with both disease severity and aging. Data on elderly COPD showed that the following factors were more frequent among the malnourished patients compared with those identified as at risk for malnutrition: living alone, not living in one’s own home, requiring daily community service and meals-on-wheels [27]. This is consistent with our observation of negative correlation between age and question G (Lives independently) of the MNA.

A potential weakness of the present study could be the age range (65–92 yrs), which precludes comparisons with younger patients. The present study was designed to focus on elderly patients with COPD. This represents a homogeneous setting, with patients sharing similar characteristics, and probably allows performance of observations and analysis targeted to this population, also taking into account the fact that a reasonably wide age range, including almost three decades (65–92 yrs), was studied. While it must be recognised that a comparison with younger subjects may have added valuable information, it must be underlined that COPD at a younger age is relatively uncommon or at earlier stage, and so it would have been hard to enrol significant numbers of much younger patients with similar clinical phenotypes.

The choice of any assessment instrument (including MNA) could be questionable, because many variables and, consequently, tools may be used to assess malnutrition. It has to be taken into account that no single measurement has emerged as gold standard in defining malnutrition in the elderly [9, 14]. However, the use of the MNA questionnaire seems a suitable choice because it explores all three determinants of the nutritional status [9], and the European Society of Parenteral and Enteral Nutrition endorsed it as a recommended screening tool in the elderly [14]. Another potential limitation of the study concerns the submission of the full MNA questionnaire to all patients, regardless of screening score. It should be considered that originally, the MNA was developed in its full version (18 items) and only subsequently the short form (that is the screening; six items) was developed [18]. The authors who developed the MNA pointed out that the MNA short form can be used with confidence; however, administering the full MNA might be more efficient in some settings [18]. The screening is only a way to save time in some clinical situations, while the full MNA is appropriate in all kinds of elderly patients. In addition, the statistical analysis shows the absence of difference between subjects who did or did not complete the full MNA (see Methods section).

MNA was originally designed as a composite tool in which various domains contribute to the final score [18]. As such, the individual validity of each domain may be questioned. However, previous studies on malnutrition in the elderly have shown that lower dietary score distinguishes between malnourished and at-risk populations better than body composition and body function domains of the MNA [28].

Several mechanisms may explain the finding that ageing and COPD determine malnutrition by acting on different aspects of the nutritional status. In COPD patients, both physical inactivity due to exercise intolerance [29] and systemic inflammation [3] may explain the prevalent loss of fat-free mass. In addition, the expansion of extracellular and intracellular water volumes, driven by hypoxaemia, may explain why malnutrition may occur despite normal weight [30]. However, in elderly subjects, weight loss and malnutrition are highly prevalent and variously depend upon physical, social and medical factors [7]. The observed negative correlation between ageing and energy intake might be due to nutritional (e.g. loss of taste, poor dentition, dysphagia, poor chewing and swallowing ability, poor appetite or food aversion) and social (e.g. living or eating alone or poverty) problems, and to decreased energy and inability to self feed. Furthermore, many age-related medical factors (comorbidity, polypharmacy, infections, fractures, dementia and physical disability) can contribute to a link between ageing and body functionality, as found in this study. Body functionality includes several variables that can be causes or effects of malnutrition at the same time. Nevertheless, as stated by Chen et al. [31] “malnutrition in the elderly is a multidimensional concept encompassing physical and psychosocial elements. It is precipitated by loss, dependency, loneliness and chronic illness”. With this perspective, the management of malnutrition in the elderly COPD can not only include “nutrients”. Consistent with this and taking together the present results on correlations between GOLD stage, and age, Mobility (item C) and Subjective perception of health status (item P) appear susceptible to specific intervention, such as rehabilitation or treatment of depression. As a result, a pure nutritional intervention is highly unlikely to improve nutritional status and physical performance in COPD [32], while only an integrated multidimensional intervention centered on rehabilitation is likely to succeed. The favourable findings in both very old and frail patients [33] and in selected COPD populations [34, 35] support this conclusion. Within this setting, particular attention is warranted by depression as a factor susceptible of intervention: in fact, an association between malnutrition, as assessed by MNA, and depressive symptoms has been demonstrated [36].

In conclusion, the results of the present study suggest that severe COPD and ageing are independent and probably concurrent conditions leading to malnutrition. COPD influences aspects related to body composition, whereas both COPD and ageing contribute to poor body functionality. The present findings should be considered preliminary, due to the cross-sectional design and the small size of the correlation coefficients. Nevertheless, they probably contribute to our understanding of the complex relationship between COPD severity, ageing and nutritional status.