The prevalence of and risk factors for dysphagia among elderly residents in nursing homes: a systematic review and meta-analysis

DOI: https://doi.org/10.21203/rs.3.rs-808140/v1

Abstract

Background

Elderly residents in nursing homes are at high risk for dysphagia. However, the prevalence estimates of this condition and its risk factors among this population were inconsistent.

Objective

To estimate the prevalence of dysphagia and examine its risk factors among the elderly in nursing homes.

Methods

Electronic database of PubMed, Web of science, Embase for English language, Wangfang, VIP and CNKI for Chinese language were systematically searched to identify relevant observational studies published not later than July 4, 2021. Studies conducted in nursing homes and reported dysphagia assessment methods were included.

Results

In total, 43 studies involving 56,746 participants were included in this systematic review and meta-Analysis. The overall pooled crude prevalence of dysphagia was 35.9% (95%CI: 29.0%, 43.4%), with high heterogeneity (I2 = 99.5%). There was a statistically significant difference in prevalence estimates with respect to study locations, methods of assessment of dysphagia, dysphagia assessment staff, representativeness of samples, and validity of assessment tools. Pooled estimates indicated that male (OR = 1.13, 95%CI: 1.00, 1.27), cognitive impairment (OR = 2.47, 95%CI: 1.59, 3.84), functional limitation (OR = 2.59, 95% CI: 1.75, 3.84), cerebrovascular disease (OR = 2.90, 95%CI: 1.73,4.87), dementia (OR = 1.50, 95%CI: 1.15, 1.96) and Parkinson’s disease (OR = 1.81, 95%CI: 1.06, 3.08) were significant risk factors for dysphagia.

Conclusions

The prevalence of dysphagia in nursing homes is relatively high, and with high heterogeneity. Also, many factors were associated with the risk of dysphagia. Further research is needed to identify strategies for management and interventions targeted at these disorders in this population.

Background

Dysphagia was listed as one of the geriatric syndromes in the European Union Geriatric Medicine Society white paper in 20161. It may lead to adverse physical consequence and fatal complications, such as aspiration pneumonia, malnutrition and dehydration2-4. Although diet is a pleasant social activity, people with swallowing problems were more likely to report depression symptoms and lower quality of life5 6. Studies suggest that residents in nursing homes experience high rates of dysphagia. However, estimates of the prevalence of dysphagia in nursing homes varied across studies from 15% to 70%7. This variation may be explained by various assessment methods of dysphagia. In this regard, there is lack of reliable estimate of dysphagia prevalence among the elderly in nursing homes in the current literature. Furthermore, several risk factors associated with dysphagia have been reported, some of which are having advanced age, functional limitations, history of dementia, cognition impairment, and neuromuscular impairments 8-10. These also varied across studies, and most of which were done in clinical or community settings. 

Reliable estimates of the prevalence of dysphagia, and identification of risk factors for dysphagia, are important for informing efforts to prevent and treat swallowing problems and its complications, especially in nursing homes where this condition has frequently been reported. Therefore, we conducted this systematic review and meta-analysis to estimate the prevalence of dysphagia among the elderly in nursing homes and explore its risk factors. 

Methods

Data sources and search strategy

This systematic review and meta-analysis of scientific peer-reviewed literature were performed using the recommendations from the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline (See Table S1 in supplement).

A systematic literature search for English studies published not later than July 4, 2021 was conducted in the Embase, PubMed, and Web of Science databases. A systematic literature search for Chinese studies was also conducted in the WanFang, CNKI and VIP databases. All these searches focused on studies that assessed the prevalence and risk factors of dysphagia in nursing homes. The following search terms were used: (swallowing OR swallowing disorder OR swallowing impairment OR dysphagia OR deglutition disorder OR swallowing difficulty OR swallowing dysfunction OR swallowing problem OR oropharyngeal dysphagia OR esophageal dysphagia) AND(assisted living facility OR care facility OR nursing home OR homes for the aged OR long-term care OR care home OR institutionalized elderly OR residential aged care facility OR skilled nursing facility OR institution OR residential care). References in the retrieved papers and citations of relevant reviews were checked and hand searched for further references and to minimize the chance of missing substantial studies. Gray literature was not included in this study.

Inclusion criteria  

    Studies that met the following criteria were included for data extraction: (1) reported data on individual dysphagia with 60 years or older, (2) observational study design, (3) published in peer-reviewed journals, (4) reported dysphagia assessment method, and (5) conducted in nursing homes. Reviews, case reports, and conference abstracts were excluded. 

Data extraction and quality assessment 

    Two independent authors (Zhao Hu and Baohua Zheng) retrieved relevant literature. The first-round screening was performed based on the title and abstract to exclude irrelevant studies. Next, the remaining articles were screened based on full text, and articles that did not meet the inclusion criteria were excluded. Any discrepancies on the selected studies were resolved by consensus with another author (Huilan Xu). Data extraction was performed using a standardized data collection form including first author and published year, study location, study design, sample size, age of participants, swallowing assessment method and prevalence of dysphagia. When there were studies involving the same population, only the most comprehensive or recent publications were included. 

    The same two authors independently assessed the risk of bias of these studies using a modified version of the Newcastle-Ottawa scale, which assesses sample representativeness and size, comparability between respondents and non-respondents, Assessment method of dysphagia and quality of descriptive statistics reporting (details are described in the supplement materials method S1). Studies were judged to be at low risk of bias (³3 points ) or high risk of bias(<3 points). Any discrepancies were resolved by discussion and adjudication with another author (Huilan Xu).

Statistical analysis 

    Prevalence estimates of dysphagia in nursing homes were calculated by pooling the study-specific estimates using the random-effects meta-analyses that accounted for between-study heterogeneity. If data were extracted from a longitudinal study, only the rate from baseline measurements was included in the analyses. As the distribution of prevalence estimates in the original datasets was positively skewed, all estimates were transformed using a logit in order to meet the parametric assumption of normality. Standard c2  test and Istatistic were used to assess between-study heterogeneity. Ivalues of 25 % and 75 % were used as the criteria for classifying the degree of intertrial heterogeneity, namely low heterogeneity (I2 < 25 %), moderate heterogeneity (25 %≤ I 2 < 75 %), and high heterogeneity (I2≥ 75 %).

Sensitivity analyses were conducted by omitting 1 study in each turn to determine the influence of individual studies on the overall prevalence estimates. Subgroup analyses were conducted to explore the potential sources of heterogeneity according to prespecified study-level characteristics as follows: location (Asia, Europe, North America, South America, and global), study design (cross-sectional or prospective), assessment method of dysphagia (subjective, objective, and subjective and objective), self-report of dysphagia (yes and no), country (China and all other countries), publication year (before 2010 or 2010 and after), assessment staff of dysphagia (SLP attend or not), and Newcastle-Ottawa Scale components risk of bias (low and high). Publication bias was visually assessed using funnel plots, and quantified by the Egger’s test, when more than 7 studies were used to pool data. 

    The meta-analysis of association between risk factors and dysphagia was performed using a random effects model to ensure stability and reliability of the results, regardless of the degree of heterogeneity. All analyses were performed using R software version 4.0.2 (R Foundation for Statistical Computing). Statistical tests were 2-sided and used a significance threshold of < 0.05.

Results

3.1 Literature search 

A total of 2301 records were identified through electronic database searching (Pub Med : 651; Wos: 735; Embase: 664; Wangfang: 211; Vip: 25; CNKI: 15). After removing duplicate records (n=857), 1446 records remained to be screened for title and abstract. Therefore, 1,365 records were excluded after reading the title and abstract, which left 81 articles to be assessed for eligibility. Then, 38 studies were excluded for not reporting assessment method for dysphagia (n=20), for having study subject as facility rather than participants (n=3), for not conducted in nursing homes (n=7), for having study participants from the same sample (n=2) and for being intervention or pilot studies (n=6). In the end, 43 studies met the inclusion criteria and were included in the systematic review and meta-analysis. The flowchart of the study selection process is presented in Figure 1. 

Figure 1. The flowchart of the study selection process

3.2 Characteristics of the included studies 

The characteristics of the included studies are shown in Table 1. Forty-two studies involving a total of 56,746 individuals from the four continents (Europe, North America, South America, and Asia) were included in the analysis. Among these, 35 were cross-sectional studies and 8 were longitudinal studies. The sample size ranged from 30 to 23,549 participants. Various dysphagia assessment methods were used including mealtime screening tool, eating assessment tool-10 items (EAT-10), water swallow test (WST), 3-Ounce Water Swallow Test (3 oz WST), modified water swallow test (MWST), Yale Swallow Protocol (YSP), Gugging swallowing screentest (GUSS), flexible endoscopic evaluation of swallowing (FEES), videofluoroscopic swallowing study (VFSS), clinical swallow evaluation (CSE). Two studies used a polar question, whereas one study used two questions to assess dysphagia. Mean age of participants in most of the studies was more than 80 years. The assessment staff included speech pathologist or therapist (SLP), dentist, clinician staff, nurse and self-reported. Four studies were at high risk of bias and others were at low risk of bias. The total Newcastle-Ottawa score for the studies appear in Table S2 in the supplement material.  

 

Table 1 Characteristics of included studies

First author, year

Study design

Study location

Sample size

Age(years)

gender

Dysphagia assessment method

Dysphagia assessment staff

Prevalence(%)

Steele,199711

Cross-sectional

Canada

349

Mean:87

Male:69 

Female:280

mealtime screening tool

SLP

68

Langmore,199812

longitudinal

USA

41

60 or older

NA

FEES

Clinician

60.98

Kayser-Jones,199913

Cross-sectional

USA

82

Mean:83.4

NA

CSE

SLP

55

Lin,200214

Cross-sectional

Taiwan

1221

Mean:77.07

Male:634

Female:587

self-report; neurological examination; timed WST

Nurses

51.0

Kumlien, 200215

Cross-sectional

Sweden

40

Median:80

NA

RAI

Nurses

22.5

Boczko,200616

Cross-sectional

USA

199

Mean:79.9

Male:74

Female:125

dysphagia screening tool;

CSE

Self-report;

Clinician

15

Han, 201217

Cross-sectional

China

931

Mean:83.9

Male:504

Female:427

Neill dysphagia screening test

NA

32.5

Takahashi,201218

longitudinal

Japan

647

Mean:85.1

NA

Screening checklist

Caregiver report

26.43

Bomfim,201319

Cross-sectional

Brazil

30

Mean:83.75

NA

CSE

SLP

63.3

Nogueira,201320

Cross-sectional

Portugal

266

Mean:82

Female:75%

DST, 3 oz WST

Self-report;

SLP

DST:40.1

3 oz WST:38.2

Park,201321

Cross-sectional

South Korea

395

Mean:80.7

Male:93

Female:302

GUSS

Nurses

52.70

Chen, 201422

Cross-sectional

China

400

60 or older

NA

CNSAT

NA

52.5

Maarel-Wierink, 201423

Cross-sectional

Netherlands

8119

Mean:84.0

Female:74%

Polar question

Self-report

9

Lindroos,201424

Cross-sectional

Finland

1466

Mean:83

Female:78%

Polar question

Caregiver
 report

11.8

Chen,201525

Cross-sectional

China

276

65 or older

NA

dysphagia screening tool

NA

41.3

Murakami, 201526

Cross-sectional

Japan

255

Mean:85.2

Male:58

Female:197

MWST

Dentists

15.69

Sarabia-Cobo, 201627

longitudinal

Spain

2384

Mean:88.7

Female:73.4%

EAT-10;3 oz WST

Clinician

69.6

Santos, 201628

Cross-sectional

England

166

elderly

NA

Medical record

HCPs

22.9

Wakabayashi, 201629

Cross-sectional

Japan

89

Mean:84

Male:20

Female:69

EAT-10

Self-report

29

Hollaar, 201730

Cross-sectional

Netherlands

373

Mean:83.3

Male:113

Female:260

Medical record

SLP

16

MacDonald,201731

Cross-sectional

Canada

639

Mean:87

Male:199

Female:440

STAND;90 ml WST; mealtime observation

NA

59.2

Okabe, 201732

Cross-sectional

Japan

238

60 years or older

Male:52

Female:186

MWST

Dentists

18.5

Pu,201733

Cross-sectional

Hong Kong

865

Mean:84.5

Male:259

Female:606

WST

SLP

57.10

Rech,201734

Cross-sectional

Brazil

123

60 years or older

Male:42

Female:81

CSE

SLP

60.98

Streicher,201735

Cross-sectional

19 countries

23549

65 years or older

Male:5734

Female:17815

Polar question

Caregiver report

13.4

Brochier, 201836

Cross-sectional 

Brazil

115

60 years or older

Female:67.0%

CSE

SLP

60.9

Huppertz,201837

Cross-sectional

Netherlands

6349

Mean:84.5

Female:70.2%

Two questions

Self-report

12.1

Wakabayashi, 201838

Cross-sectional

Japan

176

Mean:85

Male:39

Female:137

DSS 

multidisciplinary coworkers

92.05

Yatabe, 201839

Cross-sectional

Japan

236

Mean:87.7

Male:52

Female:184

MWST

Dentists

16.9

Gao, 201940

Cross-sectional

China

997

Mean:70.4

Male:480

Female:517

WST

SLP

25.98

Jukic-Peladic,201941

longitudinal

Italy

1490

Mean:83.5

Female:71.5%

CSE

HCPs

12.8

Hägglund,201942

longitudinal

Sweden

391

Mean:84.0

Male:182

Female:209

WST

Dentists and SLP

55.3

Hoshino, 201943

longitudinal

Japan

312

Mean:84.6

Male:69

Female:267

MWST

Dentists

16.3

MacDonald,201944

Cross-sectional

Canada

397

Mean:86.8

Female:66%

STAND

NA

10

Wu,2019

Cross-sectional

China

600

65 years or older

NA

WST

NA

66.2

Chen,2020

Cross-sectional

China

775

Mean:81.3

Male:305

Female:470

EAT-10

Self-report

31.1

Horgan,202045

Cross-sectional

Germany

100

Mean:71

Male:42

Female:58

Medical record

SLP

 

35

Imaizumi,202046

Cross-sectional

Japan

413

Mean:84.4

Male:111

Female:302

Dysphagia screening questionnaire;EAT-10

Self-report

55.4

Ward, 202047

longitudinal

USA

240

Mean:77

Male:51.7%

Female:49.3%

YSP 

Clinician

67

Simoes,202048

Cross-sectional

Brazil

280

70 or older

Male:174

Female:106

MWST

NA

45.71

Kulvanich202149

Cross-sectional

Japan

37

Mean:88

Male:5

Female:32

MWST

Clinician

35

Zhang, 202150

Cross-sectional

China

645

65 and older

Male:258

Female:397

Ohkuma questionnaire

Self-report

24.96

Izumi, 202151

longitudinal

Japan

52

65 and older

Male:11

Female:41

MWST

NA

25

SLP: Speech pathologist or therapist; CSE: clinical swallow evaluation; FEES: fiberoptic endoscopic evaluation of swallowing; WST, Water Swallow Test; STAND: Screening Tool for Acute Neuro Dysphagia; CNSAT: Clinical Nursing Swallowing Assessment Tool; MWST: modified Water Swallow Test; DSS: dysphagia severity scale; DST: dysphagia self-test; GUSS: Gugging swallowing screentest; HCPs: healthcare professions; EAT-10:10-items Eating Assessment Tool. YSP: Yale Swallow Protocol.

 

 

3.3 Prevalence of dysphagia in nursing homes   

The prevalence estimates of dysphagia reported by the individual studies ranged from 9% to 92%. Meta-analytic pooling of the prevalence estimates of dysphagia reported by the 43 studies showed a crude summary prevalence of 35.9% (95%CI: 29.0%, 43.4%), with significant evidence of high between-study heterogeneity (Q=8421.3,τ2=1.07, I2=99.5%, P<0.001). The results are shown in Figure 2. Sensitivity analysis, for which the meta-analysis was serially repeated after omission of each study, demonstrated that no individual study affected the overall prevalence estimate by more than 1% (Table S3 in the supplement material).

Figure 2 The prevalence estimates of dysphagia in nursing homes

 To further characterize the range of dysphagia prevalence estimates identified by these methodologically diverse studies, subgroup meta-analyses with subgroups defined by assessment method, study design, assessment staff, study location, risk of bias and Newcastle-Ottawa scale components were conducted. The subgroup analysis results are shown in Table 2. No statistically significant differences in prevalence estimates (Q=0.17, P=0.679) were noted between cross-sectional studies (35.2%, 95%CI: 27.7%, 43.4%) and longitudinal studies (39.1%, 95%CI: 23.8%, 57.0%). However, there was a high significant difference in the prevalence estimates from studies conducted in different study locations (P<0.001). Further, significantly lower prevalence estimates (Q=8.22, P=0.004) were found among studies only using self-report method to assess dysphagia (20.6%, 95%CI: 13.0%, 31.1%) compared with those using mixed methods (40.1%, 95%CI: 32.3%, 48.4%). Dysphagia prevalence estimates from studies that used SLP to assess dysphagia (50.2%, 95%CI: 36.8%, 63.6%) were significantly higher (Q= 8.70, P=0.013) than those from studies that did not use SLP to assess dysphagia (27.1%, 95% CI: 20.0%, 35.7%). 

As regards the Newcastle-Ottawa criteria components, lower prevalence estimates of dysphagia (Q= 8.18 ,P=0.004) were found among studies with more representative samples (54.2%, 95% CI: 42.5%, 65.6%) than among studies with less representative samples (33.7%, 95%CI: 36.6%, 41.6%). Further, higher prevalence estimates (Q= 28.54, P<0.001) were found among studies using validated assessment tools (41.0%, 95%CI: 33.5%, 49.0%) than among those not using valid assessment tools (15.4%, 95%CI: 11.2%, 20.9%). There were no statistically significant differences in prevalence estimates when studies were stratified by sample size, respondent and nonrespondent comparability, thoroughness of descriptive statistics reporting and risk of bias (P>0.05 for all comparisons). 

Visual inspection of the funnel plot of the eligible studies revealed significant asymmetry (Figure S1 in supplement material). Thus, there was evidence of publication bias as shown by the Egger’s test (P=0.003).

Table 2 Subgroup analysis of prevalence estimates of dysphagia

Characteristics

Studies 

Prevalence(95%CI)

I2 statistics

statistics

P-value

Study design 

 

 

 

 

 

Cross-sectional 

35

35.2%(27.7%,43.4%)

99.4%

0.17

0.679

Longitudinal

8

39.1%(23.8%,57.0%)

99.4%

 

 

Publication year 

 

 

 

 

 

  Before 2010

6

43.8%(27.1%,62.0%)

96.2%

0.84

0.360

  2010 and after 

37

34.7%(27.4%,42.8%)

99.5%

 

 

Study location 

 

 

 

 

 

Asia

20

37.5%(28.3%,47.7%)

98.0%

214.07

<0.001

Europe

11

24.4%(15.3%,36.4%)

99.7%

 

 

North America

7

44.8%(25.8%,65.4%)

98.2%

 

 

South America

4

56.3%(48.0%,64.2%)

77.2%

 

 

Global 

1

13.4%(12.9%,13.8%)

-

 

 

Country 

 

 

 

 

 

All other countries

34

34.3%(26.3%,43.4%)

99.5%

1.34

0.248

  China

9

41.9%(32.8%,51.6%)

98.4%

 

 

Dysphagia assessment method 

 

 

 

 

 

Subjective

6

24.1%(14.1%,38.2%)

99.4%

3.17

0.205

Objective 

33

37.6%(29.5%,46.5%)

99.3%

 

 

Subjective and objective

4

41.8%(22.2%,64.3%)

99.0%

 

 

Self-report of dysphagia

 

 

 

 

 

  Yes

8

20.6%(13.0%,31.1%)

99.2%

8.22

0.004

  No

35

40.1%(32.3%,48.4%)

98.6%

 

 

Dysphagia assessment staff 

 

 

 

 

 

  SLP attend 

13

50.2%(36.8%,63.6%)

97.8%

8.70

0.013

  SLP not attend 

22

27.1%(20.0%,35.7%)

99.6%

 

 

  Not clear 

8

39.9%(26.9%,54.5%)

98.1%

 

 

Sample size

 

 

 

 

 

  ³100 participants 

36

35.1%(27.4%,43.6%)

99.6%

0.52

0.469

  <100 participants

7

40.5%(28.9%,53.3%)

82.7%

 

 

Representativeness of sample

 

 

 

 

 

  Good

38

33.7%(26.6%,41.6%)

99.5%

8.18

0.004

  Poor 

5

54.2%(42.5%,65.6%)

91.9%

 

 

Comparability of respondents

 

 

 

 

 

  Good

15

33.4%(24.0%,44.4%)

99.4%

0.29

0.593

  Poor

28

37.3%(28.3%,47.3%)

99.5%

 

 

Valid assessment tool 

 

 

 

 

 

Yes

36

41.0%(33.5%,49.0%)

98.6%

28.54

<0.001

No

7

15.4%(11.2%,20.9%)

96.1%

 

 

Quality of descriptive statistics 

 

 

 

 

 

  High

38

35.4%(28.1%,43.4%)

99.5%

0.15

0.703

  Low

5

39.6%(21.7%,60.8%)

98.6%

 

 

Risk of bias 

 

 

 

 

 

Low

37

34.9%(27.6%,43.1%)

99.6%

0.49

0.484

High

6

41.9%(25.3%,60.6%)

97.2%

 

 

 

3.4 Risk factors of dysphagia in nursing homes 

A total of twenty-two studies reported potential risk factors of dysphagia in nursing homes. The potential risk factors were older age, male, less education, cognition impairment, depression symptoms, feeding dependence, less teeth, CVD, cerebrovascular disease, COPD, functional limitation, long feed time, solid food, malnutrition, underweight, comorbidity, Parkinson’s disease, dementia, pneumonia and absence occlusal support.

The pooled data from 16 studies showed that males were more likely to report dysphagia than females (OR=1.13, 95%CI: 1.00, 1.27), with a moderate heterogeneity (I2=53%; Supplement Figure S2). No significant publication bias was observed for this association (P=0.168; Supplement Figure S3). Also, the pooled data from 6 studies indicated that cognitive impairment was significantly associated with an increased risk of dysphagia (OR=2.47, 95%CI: 1.59, 3.84), with high heterogeneity (I2=87%; Supplement Figure S4). 

The pooled data from 9 studies showed that functional limitation was significantly associated with an increased risk of dysphagia (OR=2.59, 95%CI: 1.75, 3.84), with high heterogeneity (I2=96%; Supplement Figure S5). No significant publication bias was observed for this association (P=0.363; Supplement Figure S6). The pooled data from 13 studies indicated that cerebrovascular disease was significantly associated with an increased risk of dysphagia (OR=2.53, 95%CI: 1.58, 4.05), with high heterogeneity (I2=94%; Supplement Figure S7). No significant publication bias was observed in this association (P=0.423; Supplement Figure S8). Furthermore, the pooled data from 6 studies indicated that Parkinson’s disease was significantly associated with an increased risk of dysphagia (OR=1.81, 95%CI: 1.06, 3.08), with moderate heterogeneity (I2=65%; Supplement Figure S9). The pooled data from 11 studies indicated that dementia was significantly associated with an increased risk of dysphagia (OR=1.50, 95%CI: 1.15, 1.96), with high heterogeneity (I2=81%; Supplement Figure S10). No significant publication bias was observed in this association (P=0.195; Supplement Figure S11). Meta-analysis was not conducted for other factors due to insufficient data. The results are shown in Table 3.

Table 3 Risk factors for dysphagia in nursing homes

Risk factor

Included studies(n) 

Pool

OR(95%CI)

Heterogeneity

(I2)

P value for publication bias

Male

16

1.13(1.00,1.27)

53%

0.168

Cognitive impairment

6

2.47(1.59,3.84)

87%

-

Functional limitation

9

2.59(1.75,3.84)

96%

0.363

Cerebrovascular disease

13

2.53(1.58,4.05)

94%

0.423

Parkinson’s disease

6

1.81(1.06,3.08)

65%

-

Dementia

11

1.50(1.15,1.96)

81%

0.195

Discussion

This is the first systematic review and meta-analysis to explore the prevalence of and potential risk factors for dysphagia in nursing homes. This systematic review and meta-analysis included 43 original studies involving 56,146 residents in nursing homes, and demonstrated that 35.9% (95%CI: 29.0%, 43.4%) was the estimated pooled prevalence of dysphagia. Among these included studies, 22 reported potential risk factors for dysphagia. The pooled estimates indicated that being male; and having cognitive impairment, functional limitation, cerebrovascular disease, dementia and Parkinson’s disease were significant factors associated with an increased risk of dysphagia. 

Therefore, the pooled prevalence of dysphagia among the nursing home residents was higher than that reported in the community dwelling elderly. For example, a cross-sectional study, using a questionnaire for dysphagia screening, conducted in a Japan community among 1,313 elderly people, reported that the prevalence rate of dysphagia was 13.8%52. A meta-analysis of 6 high quality studies in the community dwelling elderly showed that the average prevalence of dysphagia was 15%9. On the other hand, residents in nursing homes were more likely to report frailty status and suffer from many kinds of chronic disease, such as dementia, cerebrovascular disease and Parkinson’s disease53 54, which further led to swallowing disorders. Additionally, the high prevalence rate may be caused by various medical problems that trigger swallowing disorders, such as oral medication, mechanical ventilation and head and neck surgery 55 56.

  This study also observed lower prevalence estimates among studies using self-report method to assess dysphagia than among those using mixed method. Although the difference is not statistically significant, the pooled prevalence of dysphagia from studies that used objective assessment method seemed higher than that from studies which used subjective assessment method. This finding, therefore, needs further investigation. Nevertheless, an observational cohort study conducted in Maryland found that about 72% of elderly women demonstrated swallowing dysfunction following a 3-ounce water swallowing test, but the participants reported few symptoms of dysphagia on a swallowing function questionnaire 57. Another study found that 80% of the residents in the long-term care homes, who failed the swallowing screening test, did not previously report that swallowing was an issue. Nevertheless, that study indicated that cognition level was not a related factor of the accuracy in reporting swallowing status 44. Therefore, further studies are warranted to explore the related factors for such a gap.

This study has also shown the significance of assessment tools for dysphagia, and the staffs attending to dysphagia in nursing homes. For example, our study found that higher prevalence of dysphagia was reported when dysphagia was assessed by SLP, and when a validated assessment method was used. Even though numerous methods or tools were exploited for dysphagia assessment, many of them had not been validated for use in this population. Therefore, different assessment procedures, assessment tools and assessment staff might have contributed to the high between-study heterogeneity. This may suggest the need for the development of formal and systematic programs for dysphagia screening and assessment in nursing homes. Noteworthy, even though the high prevalence estimate of dysphagia in nursing homes was found in this study, the management situation in nursing homes is poor. For instance, a national survey in Norway found that the residents in nursing homes were not routinely screened or assessed for swallowing problems among approximately 75% of the nursing homes, lacked oral hygiene strategies in over 80% of the nursing homes, and did not have access to external experts, including speech therapists in almost 50% of the nursing homes 58. Thus, this is significant evidence to support the idea of training and up-skilling staff in nursing homes, and raising awareness of the serious consequences of dysphagia. 

  Similar with the systematic review on the community dwelling elderly9, our study found that functional limitation, cerebrovascular disease, dementia and Parkinson’s disease were significant factors associated with the increased risk of dysphagia in nursing homes. Besides, being male and cognitive impairment were significant factors associated with the increased risk of dysphagia. A combination of factors has been reported to place residents in nursing homes at an increased risk for dysphagia, which is related to negative health sequelae. Considering demographic factors, three studies20-22 used multivariable models to show an independent association of dysphagia with advanced age. Similarly, three studies21 33 41 used multivariable logistic regression models to show that men were more likely to suffer from swallowing problems than women. Even though gender difference in the prevalence of dysphagia was also observed in this meta-analysis, the underlying mechanisms are still unclear. Cognitive impairment and dementia may be associated with the damage or weakening of brain nerves related to the swallowing activity and function, and hence leading to dysphagia59. Moreover, functional limitation, usually measured by Barthel and Katz index, was associated with degeneration of muscle and strength, also leading to swallowing difficulties 60. However, most of the preceding risk factors of dysphagia were reported in cross-sectional studies, which cannot establish causal relationships.

Several limitations need to be acknowledged. First, the data were derived from studies that had different designs, instruments for assessing dysphagia, and location. The high heterogeneity among the studies remained largely unexplained by the variables inspected. Second, subgroup analyses were not conducted to uncover the prevalence estimates of dysphagia among specific assessment tools because numerous studies may be using multiple tools simultaneously. Finally, most of risk factors were measured by self-report, hence measurement bias was unavoidable. Further studies can calculated the strength of the association between other factors which not examined due to inadequate data and risk of dysphagia in nursing homes setting.

Conclusion

In this systematic review and meta-analysis, the summary estimate of the prevalence of dysphagia among the residents in nursing homes was 35.9%. Being male; and having cognitive impairment, functional limitation, cerebrovascular disease, dementia and Parkinson’s disease were significant factors associated with an increased risk of dysphagia. Further research is needed to identify strategies for management and interventions targeted at these disorders in this population.

Declarations

Availability of data and materials

All data generated or analysed during this study are included in this published article [and its supplementary information files].

Competing interests

The authors declare that they have no competing interests.

Funding

    This research received no external funding.

Authors' contributions

Conceptualization, ZH; Methodology, ZH; Software, ZH.; Validation, ZH and BHZ; Formal Analysis, ZH; Data Curation, ZH and BHZ; Writing – Original Draft Preparation, ZH; Writing – Review & Editing, ACK and HLX.

Acknowledgments

We gratefully acknowledge Jun Yang for her assistance with forest plots for this study.

Abbreviations

CSE: clinical swallow evaluation; FEES: fiberoptic endoscopic evaluation of swallowing; WST, Water Swallow Test; STAND: Screening Tool for Acute Neuro Dysphagia; CNSAT: Clinical Nursing Swallowing Assessment Tool; MWST: modified Water Swallow Test; DSS: dysphagia severity scale.

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