Incidence and criteria used in the diagnosis of hospital-acquired malnutrition in adults: a systematic review and pooled incidence analysis

Search results and included studies

Figure 1 summarises the search results and included studies. A total 4176 studies were identified from electronic databases and two related studies known to the authors were manually added. After removing 1725 duplicates, there were 2452 studies identified for title and abstract screening. A total of 54 studies were included in the full-text review; of these, eight authors were contacted for additional information [21, 29, 33,34,35,36,37,38]. Of the authors who were contacted, two [21, 29] were contacted to seek clarification in the methodology used to identify the incidence of HAM, and six [33,34,35,36,37,38] were contacted for additional data to extract the incidence of HAM. Four studies [35,36,37,38] were excluded from this review as additional data were not provided by the authors.

Twelve studies met the inclusion criteria (Fig. 1), published between 2000–2021 and conducted in Australia (n = 7), Europe (n = 2), North America (n = 2) and South America (n = 1).

Study design and study quality

Table 1 shows the characteristics of the included studies, of which eight were undertaken in the acute care setting [21, 28, 33, 39,40,41,42,43], three in subacute [34, 44, 45], and one across both acute and subacute combined [29]. All 12 studies were observational; of these, two were retrospective clinical audits [21, 29] and ten were prospective cohort studies [21, 28, 33, 34, 39,40,41,42,43,44,45]. Using the Quality Criteria Checklist for Primary Research, seven of the ten studies were rated positive [33, 34, 39, 40, 42, 44, 45], two neutral [28, 41], and three negative [21, 29, 43] (Table 2).

Participant characteristics

Participant characteristics are displayed in Table 1. In total there were 35,324 adult hospitalised patients across the 12 studies. In the prospective studies (in the acute and subacute setting), the sample size was between 24 to 584 adult inpatients [28, 33, 34, 39,40,41,42,43,44,45], while the two retrospective studies [21, 29] included 15,419 and 17,717 hospital admissions respectively. Of the acute prospective studies, three recruited patients from medical and surgical wards [33, 39, 43], one recruited oncology patients undergoing high-dose conditioning and autologous peripheral blood stem cell transplantation [28], and one recruited acute hip fracture patients admitted for surgical intervention [40]. The remaining two acute prospective studies, failed to specify the acute ward or unit where participants were recruited [41, 42]. All three prospective subacute care studies included patients aged ≥65 yrs admitted to geriatric evaluation and management units in Australia [34, 44, 45].

Definition of hospital-acquired malnutrition

Of the twelve included studies, only two provided specific definitions of HAM [21, 29]. The remaining ten studies evaluated changes in nutritional status, hence, a definition of HAM was not provided. Cheng and colleagues (2019) [21] defined HAM as “any decline in nutritional status that occurs during hospital stay, independently of nutritional status on admission, which was further categorised as “preventable” and “non-preventable” [21]. “Preventable HAM” was defined as a “decline in nutritional status in the absence of injury or inflammation (starvation related malnutrition), or a decline in nutritional status in the presence of injury or inflammation but received inadequate nutrition for the condition (disease-related malnutrition)”. While “non-preventable HAM” was defined as a “decline in nutritional status in the presence of injury or inflammation and received adequate nutrition for the condition (disease-related malnutrition)” [21]. Woodward and colleagues on the other hand, defined HAM as “malnutrition first diagnosed >14 days after admission” [29].

Incidence of hospital-acquired malnutrition and criteria used in its diagnosis

Overall, acute prospective studies reported an incidence of HAM between 9%–38% [28, 33, 39,40,41,42,43]. This is higher than that reported in retrospective studies in the acute setting (<1.4%) [21, 29] and in prospective subacute studies, which either found no cases of HAM [44] or found a HAM incidence of 7% [34, 45] (Table 1). In the acute prospective studies, it was observed that the longer the timeframe between nutrition assessment, the higher the incidence of HAM [28, 33, 39, 41, 43].

The calculated pooled incidence proportion of HAM among all the prospective studies was 21.65% (95% Confidence Interval (CI) 13.68, 29.63) with a high heterogeneity amongst the studies (I² = 92%) (Fig. 2a). When only prospective studies conducted in the acute setting were included, the pooled incidence proportion of HAM was 25.95% (95% CI = 17.33, 34.57), however, heterogeneity remained high (I² = 90%) (Fig. 2b). Further subgroup analyses were conducted to explore causes of heterogeneity. When only acute prospective studies, which used a similar timeframe between assessments and similar nutrition assessment tools or criteria were included, the incidence proportion of HAM was 31.37% (95% CI = 26.48–36.27) with a low heterogeneity (I² = 27%) (Fig. 2c).

^aBaseline assessment conducted 5 (±4 days) prior admission or up to 72 h of admission, and follow up assessment conducted at discharge. ^bNutrition assessment tools or criteria included are: the Subjective Global Assessment; the Patient Generated Subjective Global Assessment; and the 2012 malnutrition diagnostic criteria by the Academy of Nutrition and Dietetics and the American Association of Enteral and Parenteral Nutrition. CI confidence interval, SE standard error, IV inverse variance, df degrees of freedom.

Of the ten prospective studies included in this review, the SGA was used in six studies (as a stand-alone assessment or within the PG-SGA) [28, 39, 41,42,43, 45], the MNA was used by three studies [33, 34, 44], and one study used the 2012 malnutrition diagnostic criteria by the Academy of Nutrition and Dietetics and the American Association of Enteral and Parenteral Nutrition [40]. The average timeframe between nutrition assessment in acute prospective studies ranged between 7–23 days, and in the subacute studies between 17–34 days [34, 44, 45] (Table 1).

The two retrospective studies reported using the SGA to identify cases of HAM [21, 29]; however, they did not specify the number of patients who were assessed with this tool (as opposed to having the tool applied retrospectively based on information available in the medical record), and, for those who were assessed with the SGA, it was not clarified whether repeated nutrition assessments had been conducted and when. Additional information was obtained for the Woodward et al. (2020) study [29] from a recently published article which used the same data [46]. This study reported that out of the 208 patients who were clinically assessed to have developed HAM, only half (n = 104/208) were initially assessed with the SGA, however, no follow up assessment with the SGA was reported to have been performed [46].

Health outcomes associated with in-hospital nutritional decline

Three acute prospective studies found that increased length of stay (LOS) was significantly associated with nutrition status decline (independently of nutrition status on admission) [39, 41, 42]. After adjusting for confounding variables, two studies showed that LOS was still significantly longer for patients with decline in nutritional status [39, 42]. One [41] did not conduct a multivariable statistical analysis for this specific outcome, making it difficult to establish if decline in nutritional status was an independent risk factor for increased LOS.

From the Braunschweig et al (2000) study [41], patients who either experienced nutritional decline, remained malnourished, or were admitted to hospital malnourished but improved from SGA C to B and from B to A, incurred higher costs (of almost $US 10,000–$38,000 more) than patients who remained well-nourished; however univariate analysis found this to be statistically significant only for those patients who declined from SGA A to C (p ≤ 0.05) [41]. A multivariate analysis showed higher odds of complications for patients who experienced a decline from SGA A or B to C [odds ratio (OR) = 3.8 (CI 1.2,11.4) and OR = 2.4 (CI 1.0, 5.9) respectively], and from SGA C with a further 5% weight loss (OR = 3.1 (CI 1.3, 7.4) [41]. However, the authors failed to describe the types of complications identified in the study.

Lima and colleagues [42] evaluated if in-hospital mortality, 6-month mortality and 6-month hospital readmission was associated with decline in SGA category in the first week of acute admission. Only 6-month readmission rates were significantly higher for patients with decline in nutritional status (p = 0.03); this was still significantly higher after a multivariate analysis [OR = 3.59 (CI 1.05, 12.26)] [42].

Certainty of the evidence

Table 3 summarises the GRADE certainty of the evidence for the association between in-hospital nutritional decline and each outcome identified in the acute prospective studies [39, 41, 42]. The certainty of the evidence was moderate for LOS [39, 41, 42] and re-admission in 6 months [42], and low for infections and complications [41]. The certainty of evidence was downgraded due to serious bias (neutral quality of one study [41]) and imprecision due to the limited sample sizes/events.