Malnutrition risks and their associated factors among home-living older Chinese adults in Hong Kong: hidden problems in an affluent Chinese community

Malnourished older people have poorer functional status [1‐3], longer hospital stays [4‐7], and increased readmissions [4], morbidity [5] and mortality [4‐7]. Early nutritional screening with community interventions would help to identify older adults at risk of malnutrition and improve their nutritional status in a timely manner [8].

Previous literature has identified various risk factors of malnutrition in the community of older adults. Certain socio-demographic characteristics are associated with that risk: older age [9‐17], female sex [9, 10, 15, 16, 18, 19], unmarried [16, 20], low education level [10, 12, 16, 18, 19, 21], unemployment [19], low income [18, 21], living alone [12, 19], lifestyle choices including smoking [22] and less physical activity [21], health status including comorbidity [11], the use of dentures [23], chewing difficulty [20, 24, 25] and poor appetite [25, 26]. Although other factors such as alcohol intake [14, 22] and financial support [15, 18, 19] have been investigated, the findings are inconsistent. The relationship between visual or hearing impairment, which is common in older people, and malnutrition are less studied. As for dietary factors, older adults with decreased food intake and fewer meals [13], difficulty in food preparation [27, 28], and less consumption of fruit and vegetables [17, 20, 29, 30], meat [17, 29], milk [30] and other fluids [29] are more prone to malnutrition. However, the relationship between adherence to local dietary guidelines, or dietary behaviour such as meal skipping and food preferences and malnutrition, have been less investigated.

Because of the one-child policy [31], China is facing the problem of an ageing population, with about 30% projected to be older people aged above 60 by 2050 [32]. Among 1.4 billion Chinese, one-fifth of the world’s population, only a few studies exist studying malnutrition [11, 33]. Using Mini Nutritional Assessment (MNA), Han et al. found about 44% of the community Chinese older adults either at risk, or already suffering from malnutrition [11], while Ji et al. identified about 76% of those aged 90 and over were at risk of malnutrition [33]. However, these previous studies were conducted in developing cities. The more affluent cities in China with gross domestic over US$300 billion, such as Hong Kong and other Tier 1 cities, share many similarities with developed countries, such as a smaller family structure and physical inactivity, which may worsen the malnutrition problem. With rapid economic growth in China, a study from an affluent Chinese society is needed to serve as a model for the rapidly developing and ageing future society in mainland China. The aim of this study is therefore to examine the malnutrition risk and identify its associated factors in home-living older Chinese adults in Hong Kong.

A total of 613 subjects completed the survey without missing data on MNA were included in the study (response rate = 52.0%) (Fig. 1). With 54.0% females, the sample collected matched the sex distribution of the Hong Kong older population [48]. The mean age of the subjects was 78.5 ± 7.4, ranging from 60 to 106 (Table 1). The majority had only primary or lower educational attainment (72.8%), were receiving CSSA (59.5%) and living alone (63.3%). About half of the subjects (49.5%) had at least one chronic condition, with total CCI score greater than zero. A considerable proportion reported visual (56.0%) or hearing impairment (41.4%), and more than half reported the use of dentures (63.9%). A large proportion did not adhere to dietary guidelines on the vegetable (82.9%), fruit (72.9%), meat (93.3%) and milk (80.4%) groups, with at least 80% below the recommendations. The majority cooked food for themselves (78.5%) and did not take dietary supplements (63.0%).

The nutritional status of the subjects is shown in Fig. 2. The mean MNA score was 24.9 ± 2.8 and ranged from 15 to 29.5. Nearly 30% of the subjects had MNA below 24, indicating they were either at risk of malnutrition (28.1%) or already malnourished (1.1%). Compared with subjects having normal nutrition status, those who were at risk or malnourished had significantly higher proportion receiving CSSA, poorer visual and hearing ability and usual appetite, more chewing difficulty and main meal skipping behaviour, and different food preference and were less active and below recommendation of the dietary guidelines of grains, vegetables and fruits (all p < 0.05) (Table 1).

The results of the univariate analyses of socio-demographic and lifestyle characteristics, health status and dietary factors associated with at risk or malnourished nutritional status are to be found in Table 2. A backward multivariable logistic regression analysis using those factors with p-values < 0.25 in the univariate analysis revealed that (1) visual ability, (2) usual appetite and (3) main meal skipping behaviour were significantly and independently associated with at-risk or malnourished status (Table 2). Compared with those with good visual ability, older adults with only fair ability had a higher odds of being at risk or malnourished (adjusted odds ratio (AOR): 1.71, 95% CI: 1.09–2.67, p = 0.020) and those with weak ability had an even higher odds (AOR: 2.71, 95% CI: 1.68–4.35, p < 0.001). Older adults with a good usual appetite had a decreased odds of being at risk or malnourished (AOR: 0.38, 95% CI: 0.26–0.56, p < 0.001), whereas those with little usual appetite had an increased odds (AOR: 4.52, 95% CI: 1.92–10.62, p < 0.001), when compared with those who reported a normal usual appetite. Older adults skipping one or more main meals per day had an increased odds of being at risk or malnourished (AOR: 2.03, 95% CI: 1.27–3.25, p = 0.003) compared with those without main meal skipping behaviour.

It has long been believed that malnutrition is an important health issue only in less developed economies where food insecurity and infectious disease prevail [49]. Given the social and economic transformation in China, overweight and obesity have become a research and service focus [50], while malnutrition in vulnerable groups such as older adults have usually been ignored. Our study is the only one to concentrate on malnutrition of older adults in an affluent Chinese community. The findings show that nearly 30% of the subjects were at risk of malnutrition, close to the global average, which revealed that 37.7% of the community older adults were at malnourished risk or already malnourished [51]. This suggests that malnutrition is not limited to developing regions [11, 33], and that more effort should also be put into examining its underlying causes in affluent regions.

By multivariable logistic regression, the high malnutrition risk was found to be associated with (1) fair and poor visual ability, (2) lack of appetite and (3) meal skipping behaviour. Our study found the poorer the visual ability, the higher the odds of being at risk or malnourished. This is consistent with a previous study’s finding that poor vision was associated with higher malnutrition risk among older assisted-living residents [52]. Since poor vision reduces the functional status of older people [53, 54], subjects with impaired sight may find it difficult to feed themselves and go shopping for supplies, causing reduced food intake and thus malnutrition. Previous literature found that older adults having low scores in both basic and instrumental daily living activity [12, 15, 25] had a higher malnutrition risk. Visual problems are common in Hong Kong [55], but the waiting time for new case booking at eye specialist out-patient clinic is extremely long, ranging from 47 to 153 weeks for a stable case [56]. Improvement in eye care services may pose a secondary effect to improve the nutritional status in the visually impaired population.

Our findings on the relationship between poor appetite and high malnutrition risk are consistent with a Netherlands prospective cohort study [26], indicating that one does lead to the other. Poor appetite is associated with lower intake of energy and protein [57], which contributes to malnutrition. A qualitative study on home-living older adults’ views on food reported that the quality of food, including taste and fashion, was of importance [58]. The taste and smell of food can be enhanced using flavourings and seasonings to stimulate appetite [59, 60]. Old-fashioned food and increased food variety might be considered in meal planning for older people [58, 59]. In the affluent Chinese community, the reduced appetite may be caused by depression, especially when the prevalence of depression was high (12.5%) among Hong Kong older adults [61]. This indicated the need to cover multiple dimensions of geriatric problems for nutritional intervention.

In our study, subjects with meal skipping behaviour had a higher malnutrition risk, matching the findings of other studies [10, 13]. Skipping meals may imply insufficient food intake, leading to malnutrition [13]. There are several possible reasons leading to the skipping of meals. First, living alone or being alone in the daytime is widespread in developed regions with smaller family structure [62], increasing the chances of skipping meals as older people prefer not to eat alone [63, 64]. Second, older adults may skip meals because of financial constraints. A comparative study suggest that a pleasant eating environment increases older people’s energy intake at each meal [65]. Canteens for the older adults selling nutritionally balanced meals at low cost may provide a place for them to interact with one another, developing the social support that reduces loneliness and malnutrition risk [66, 67].

The strengths of our study include the use of MNA, which is a well-validated and frequently used nutrition screening tool specifically intended for older adults [36, 51], and the use of materials such as booklets with detailed procedures of anthropometric measurements, and standard sizes of bowls, cups and food models to ensure high reliability during data collection. The limitations of the study include the cross-sectional design, which cannot identify the cause-and-effect relationship between malnutrition and its associated factors, and convenience sampling, which may introduce bias. Furthermore, the local dietary guideline did not consider gender-specific food intake, which may lead to overestimation of insufficient food intake in female requiring relatively less intake than male. However, other gender-specific guidelines such as the Eatwell Guide from UK [68] were not adopted due to cultural and ethnic issues, as Caucasian has larger body size and thus higher nutrition requirement than Chinese. Although a substantial number of comorbid subjects with various diseases were included in the study, some potential subjects declined to participate because of illness, which may have led to lower comorbidity in our sample. As comorbidity is positively associated with malnutrition [11], the implication is that the malnutrition risk reported in our study may be an underestimate.

To conclude, this study found that a significant proportion of the home-living older adults were at risk of malnutrition in an affluent Chinese community, which causes much concern and deserves attention, revealing a need to examine the impacts of disparity between rich and poor on nutrition in older adults. The results of the multivariable logistic regression analysis found that, fair or poor visual ability, lack of appetite and meal skipping behaviour are associated with high malnutrition risk. Eye care services improvement is vital to reduce the problem of visual impairment and thus malnutrition. The sensory perception of flavour, wide variety and traditional types of food can improve the appetite of older adults. Older people’s canteens can be developed to allow interaction among older adults to enhance social support, while providing nutritionally balanced meals at low cost.