DOI: https://doi.org/10.21203/rs.3.rs-1064767/v1
Objective
Our objective was to understand the prevalence of sarcopenia in schizophrenic patients and to evaluate if calf circumference (CC), mid-upper-arm circumference (MUAC) and Ishii tests can be used to accurately screen for sarcopenia in schizophrenic patients.
Method
We enrolled schizophrenic patients aged 50 or older, who were regularly taking antipsychotic medications, at two mental health centres. Bioimpedance-based muscle-mass was analysed with an InBody 770 instrument, while muscle strength was measured with a digital grip-strength dynamometer. The physical performance of the patients was gauged from their gait speed over 6 m. Standard AWGS2019 diagnostic criteria were used, and the accuracies of the three screening methods were indicated by the sensitivity, specificity, receiver operating characteristic curve, positive predictive values and negative predictive values.
Results
A total of 339 stable schizophrenic patients were enrolled. The overall prevalence of sarcopenia was 53.1%, and the prevalence was, respectively, 55.6% and 47.66% for males and females. The prevalence of sarcopenia obesity in the total population was 16.22%, and that of males and females was 18.97% and 10.28%, respectively.
The CC, MUAC and Ishii test sensitivity/specificity in screening for sarcopenia were 78.3%/67%, 76.74%/68.93%, 89.92%/67%, respectively, in males and 92.16 %/69.64%, 74.51%/78.57%, 96.08%/55.36%, respectively, in females. In males, the AUCs of the CC, MUAC and Ishii test were 0.8 (95%CI, 0.744-0.856), 0.78 (95%CI, 0.721-0.84) and 0.88 (95%CI, 0.837-0.922), respectively, and in females, they were 0.893 (95%CI, 0.833-0.953), 0.843 (95%CI, 0.772-0.915) and 0.855 (95%CI, 0.784-0.926), respectively.
Conclusion
The incidence of sarcopenia in schizophrenia patients is high. Clinical doctors should screen for sarcopenia in patients with schizophrenia and provide timely interventions to reduce the occurrence of adverse events. The CC, MUAC and Ishii tests are simple and easy-to-use screening tools for sarcopenia in both males and females with schizophrenia.
Schizophrenia is a chronic disease with a high disability rate that requires long-term treatment and places serious burdens on the patient, his/her family, and society (1). Due to the low social acceptance of patients with schizophrenia, patients tend to receive treatment in mental centres for a long time, as they cannot be returned to his/her family as scheduled after the disease is controlled.Due to the lack of professional rehabilitation experts to guide exercise in most mental centers, while the lack of space in mental centers and other factors, most schizophrenics can only sit for long periods of time. Clearly, time spent sedentary and a lack of exercise are risk factors for sarcopenia (2). Sarcopenia, which is age-linked, is characterized by weakened skeletal muscle and a steadily depleting muscle mass and is linked to other serious problems, such as fractures, falls, infections, disability, even death (3–4). During hospitalization, patients with schizophrenia often have similar adverse outcomes as those with sarcopenia, such as falls, frequent infections, and a reduced life expectancy. Previous studies have shown that patients with mental illnesses experience accelerated aging, and there are subjective reports of sufferers having decreased muscle strength (5). Another study has shown that patients with schizophrenia are possibly more likely to have sarcopenia (6). The same inflammatory factors have been reported in patients with sarcopenia and schizophrenia(7).Therefore, based on the above research, we believe that sarcopenia and schizophrenia have a certain potential relationship. However, the studies have not clarified whether sarcopenia is related to schizophrenia; hence, we intended to investigate the prevalence of sarcopenia in patients with schizophrenia.
Currently, diagnosing sarcopenia requires checking muscle mass, for which there are a plethora of diagnostic tools, including dual x-ray absorptiometry,,bioelectrical impedance analysis, computed tomography, and magnetic resonance imaging. However, the above methods should be conducted on dedicated equipment by trained personnel, which may not suit all mental health centres. Rather, such institutions would benefit from a simple screening method or tool. Present studies have shown that calf circumference (CC)(8), mid-upper-arm circumference (MUAC)(9), and the Ishii test(10) have good accuracy for sarcopenia screening in communities or nursing homes, but they have not been verified in patients with psychosis. The other purpose of this study, therefore, was to verify the accuracy of the above screening tools.
Schizophrenic patients aged 50 years or older who were regularly taking antipsychotic medications at two mental health centres were included. The schizophrenic patients showed a stable condition for more than 6 months and could fully cooperate with the instructions and adhere to medication regimes. Exclusion criteria included schizophrenia instability, contraindications for BIA, uncooperative patients, those taking diuretics (with the exception of diuretics used to treat hypertension with a stable dose for ≥21 days), or other disorders or diseases deemed unsuitable by the investigator. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Institutional Review Board of the Zigong Medical Foundation (IRB number: 20191001) and the Psychiatric Hospital of Ziyang (IRB number: zjsjsbyy-kyxm-2019-2). All participants or their legal guardians provided written informed consent.
The determination of muscle mass and visceral fat area was achieved via BIA and an Inbody 770 Body Composition Analyser (Inbody 770, Biospace China Inc.), respectively. Data on the appendicular skeletal muscle mass (ASM), which is a measurement of total leg and arm musculature, and the patients’ height were collated, and the ASM index (ASMI) (kg/m2) was calculated (11). We defined obesity as a visceral fat area over 100 cm2(12).
After assessing each patient’s grip strength with a digital dynamometer (Camry EH101, Camry, El Monte, CA, USA) and their walking speed, we respectively estimated their muscle strength and physical performance. Three datapoints were recorded for the strength of each hand, and the maximum was used in comparative analysis. We timed each individual twice as they covered a walking distance of 6 m (to a 0.01 s precision), and the average time was used.
Weight, height, MUAC, and CC were the anthropometric indicators. Both weight and height were measured twice and the outcomes for each averaged. MUAC and CC were measured while the individual to be assessed was standing. The standard measurement for MUAC was conducted as follows: we marked the midpoint of the upper arm (between the acromion and olecranon) when the elbow was at 90°; then, we used a tape measure to naturally lower the subject’s arm around the midpoint of the marker. CC was measured as follows: the observer moved a tape measure up and down to determine the maximum horizontal circumference of the calf. MUAC and CC were measured to the nearest decimal point in centimetres, and two measurements on the dominant side were averaged. We recruited medical staff from hospitals to complete the study measurements, all of whom underwent the same training.
We followed the 2019AWGS consensus to define sarcopenia (10). For low muscle mass definition in males and females, the respective cut-off values were 7.0 kg/m2 and 5.7 kg/m2 ASMI. Female or male muscle strength was marked as low when a grip strength of < 18 kg or < 28 kg was recorded. Physical performance was deemed poor below a 1.0 m/s walking speed.
To judge patients for sarcopenia, we applied the upper CC thresholds of 34 cm for males and 33 cm for females (10) and minimum Ishii results of 105 points for males and 120 points for females (9).
All data were analysed on SPSS 23.0 (IBM Corp, NY, USA), and values are represented as means ± SD or medians with interquartile ranges (IQR). One-way ANOVA was used to test continuous variables, which are represented as numbers (percentages), and chi-squared tests compared qualitative variables. The area under the ROC curve (AUC) was found to evaluate the utility of the tools for identifying sarcopenia, and the DeLong method was applied to test differences in the curves (13). As CC and Ishii tests have thresholds for diagnosing sarcopenia, the existing thresholds were evaluated to calculate the corresponding specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) to evaluate the accuracy of the two screening methods. MUAC screening for sarcopenia has no cut-off point, thus we set a cut-off point that we believe predicts sarcopenia: the maximum approximation index. The corresponding specificity, sensitivity, PPV, and NPV were obtained to assess the accuracy of the screening tool.
A total of 339 stable schizophrenic patients aged 50 years or older were enrolled. The 50-59, 60-69, and ≥70 years of age group proportions were 27.73%, 48.67%, and 23.6%, respectively. 205 (60.47%) people had low muscle mass. The overall prevalence of sarcopenia was 53.1%; while in the 50-59 age group, 60-69 age group, and ≥70 age group, the prevalences were 36.2%, 54.5%, and 70%, respectively. The prevalence of sarcopenia obesity was 16.22% in the general population and, respectively, 6.4%, 18.8%, and 22.5%, in the 50-59, 60-69, and ≥70 age groups. The prevalence of sarcopenia or sarcopenia obesity increased with age.
In this study, we included 232 (68.44%) males and 107 (31.56%) females. The sarcopenia incidence was 55.6% and 47.66% and the prevalence of sarcopenia obesity was 18.97% and 10.28% for males and females, respectively. There were statistically significant differences in age, BMI, grip strength, ASMI, MUAC, CC, and Ishii test scores between the absence or presence of sarcopenia in the male and female groups; but we found no statistically significant difference in gait speed between sarcopenia and non-sarcopenia females, as shown in Table 1.
Table 1
Characteristics of the participants
|
Characteristics
|
Male |
Female |
||||
|
Non-Sarcopenia (n=103) |
Sarcopenia (n=129) |
p |
Non-Sarcopenia (n=56) |
Sarcopenia (n=51) |
P |
|
|
Age,years,iqr |
63 |
66 |
<0.001 |
64 |
66 |
0.01 |
|
BMI,kg//m2,mean(SD) |
26.28(3.67) |
22.69(3.23) |
<0.001 |
26.58(3.46) |
20.96(3.25) |
<0.001 |
|
Gait speed,m/s,n(%) |
|
|
0.026 |
|
|
0.171 |
|
≥1 |
92(47.67) |
101(52.33) |
|
41(56.94) |
31(43.06) |
|
|
<1 |
11(28.21) |
28(71.79) |
|
15(42.86) |
20(57.14) |
|
|
Handgrip strength,male<28kg,female<18kg,n(%) |
|
|
<0.001 |
|
|
<0.001 |
|
no |
49(98) |
1(2) |
|
26(100) |
0 |
|
|
yes |
54(29.67) |
128(70.33) |
|
30(37.04) |
51(62.96) |
|
|
ASMI,kg/m2,mean(SD) |
7.26(0.55) |
6.04(0.59) |
<0.001 |
6.29(0.55) |
4.96(0.46) |
<0.001 |
|
MUAC,cm,mean(SD) |
30.08(2.95) |
27(2.63) |
<0.001 |
30.89(3.33) |
26.05(3.45) |
<0.001 |
|
CC,male<34cm,female<33cm,n(%) |
|
|
<0.001 |
|
|
<0.001 |
|
no |
69(71.13) |
28(28.87) |
|
39(90.7) |
4(9.3) |
|
|
yes |
34(25.19) |
101(74.81) |
|
17(26.56) |
47(73.44) |
|
|
Ishii test score,mean(SD) |
93.98(26.26) |
138.12(27.16) |
<0.001 |
110.87(36.99) |
156.72(21.18) |
<0.001 |
|
Note:BMI:body muscle index;ASMI:appendicular skeletal muscle mass index;MUAC:mid-upper arm circumference;CC:calf circumference. |
||||||
For both sexes, we set the diagnostic thresholds to the upper Yoden index for the MUAC. Among males, the MUAC had an upper Youden index of 28.85, a 76.74% sensitivity, 68.93% specificity, and respective PPV and NPV of 0.76 and 0.7. In the female MUAC, the upper Youden index was 28.35, sensitivity was 74.51%, specificity was 78.57%, and PPV was 0.76, and NPV was 0.77. In males, the sensitivity/specificity of the CC and Ishii sarcopenia screening tests were 78.3%/67% and 89.92%/67%, and in females, they were 92.16%/69.64% and 96.08%/55.36%, respectively. In the male CC and Ishii tests, the PPV/NPV were, respectively, 0.75/0.71 and 0.77/0.84, and in females, they were 0.73/0.91 and 0.66/0.94.
The respective male AUCs of the CC, MUAC, and Ishii test were 0.8 (95%CI: 0.744-0.856), 0.78 (95%CI: 0.721-0.84), and 0.88 (95%CI: 0.837-0.922), and those for females were 0.893 (95%CI: 0.833-0.953), 0.843 (95%CI: 0.772-0.915), and 0.855 (95%CI: 0.784-0.926). When we evaluated sarcopenia in males according to the AWGS 2019 criteria, the AUCs of the CC and MUAC were much less accurate than that of the Ishii test (Table 2 and Figure 1). The three screening tool AUCs were not significantly different in the female group (Table 2 and Figure 2).
Table 2
Sensitivity/Specifificity Analyses and ROC Models for Calf Circumference, Mid-upper arm circumference and SARC-F Validation Against the AWGS 2019 Criteria
|
|
Sensitivity,%
|
Specificity, %
|
PPV |
NPV |
AUC |
|
Male |
|
|
|
|
|
|
CC<34cm |
78.3 |
67 |
0.75 |
0.71 |
0.8(0.744-0.856)c |
|
MUAC<28.85 |
76.74 |
68.93 |
0.76 |
0.7 |
0.781(0.721-0.84)c |
|
Ishii test≥105 |
89.92 |
67 |
0.77 |
0.84 |
0.88(0.837-0.922)ab |
|
Femal |
|
|
|
|
|
|
CC<33cm |
92.16 |
69.64 |
0.73 |
0.91 |
0.893(0.833-0.953) |
|
MUAC<28.35 |
74.51 |
78.57 |
0.76 |
0.77 |
0.843(0.772-0.915) |
|
Ishii test≥120 |
96.08 |
55.36 |
0.66 |
0.94 |
0.855(0.784-0.926) |
|
Note:a Significantly different relative to the CC. b Significantly different relative to the MUAC.CSignificantly different relative to the Ishii test. |
|||||
We have provided the first published analysis of the prevalence of sarcopenia in patients with stable schizophrenia, and we validated CC, MUAC, and Ishii as accurate screening tests for sarcopenia in these patients. In addition to monitoring a patient’s mental symptoms, psychiatrists should be aware that those with schizophrenia are vulnerable to developing sarcopenia. Therefore, early assessments for sarcopenia should be included in monitoring, and timely intervention provided, to reduce the occurrence of adverse events, improve quality of life, and prolong life.
We found that 60.47% of people with schizophrenia had low muscle mass and an overall sarcopenia prevalence of 53.1%, significantly higher than reported in a similar article (6). There are two potential reasons for such a large difference: the first is that our study included those over 50 years old, and the proportions of patients in the 50-59, 60-69, ≥70 years old groups were 27.73%, 48.67%, and 23.6%, respectively, while the previous study mainly included a younger cohort of 19-65 year olds. The second reason is that the studies had different inclusion and exclusion criteria: the previous study excluded many patients with physical diseases, such as a history of neurological disorders, diabetes mellitus, myopathy, goitres, and osteoporosis. Therefore, the previous study’s population was relatively healthier.
We also found that the prevalence of sarcopenia in patients with schizophrenia increased with age, and sarcopenia was more prevalent in males. Even though the population of our study is inconsistent with the population included in previous studies, the results are similar (14–15).
In this study, the AUCs of the CC and Ishii were both greater than 0.8 in males and females; therefore, these tests should be considered to have excellent prediction value(16). In females, the AUCs of the MUAC was greater than 0.8, while in males it was 0.78 (95%CI, 0.721-0.84), which is close to 0.8, and thus also has good predictive value.
The main purpose of this study was to screen for sarcopenia, and we focused on the sensitivity and negative screening of the predictive value of the model. In both sexes, the sensitivity and negative screening of the predictive value for the above three screen tools were greater than 70%, and although the Ishii test showed better sensitivity and negative predictive value, it had low specificity.
Our research had a few limitations. Firstly, the cohort was modest in size, and the next step will be to include more mental health centres for further verification.Secondly, the patients were in relatively good physical state and remined standing without difficulty for the duration of the test; therefore, sarcopenia could have been more prevalent than indicated by our outcomes.
The incidence of sarcopenia in patients with schizophrenia is high. Clinical doctors should screen for sarcopenia in patients with schizophrenia and provide timely interventions to reduce the occurrence of adverse events. The CC, MUAC and Ishii tests are simple and easy-to-use screening tools for sarcopenia in both males and females with schizophrenia.
The datasets generated and analyzed during the current study are not publicly available due to this is a database which has a lot of important information and we are applying some important projects based on this. But this datasets will be available 2 years later and is also available now from the corresponding author on a reasonable request.
2020 Zigong City Key Technology Support Plan (Project No. 2020YLSF19);
Psychiatric Hospital of Ziyang Support Plan(Project No.:zjsjsbyy-kyxm-2019-2).
Xiaoyan Chen designed the study and reviewed and edited the paper.
Ming Chen and Xiuping Lei wrote the paper.
Tian Zhu and qiuxia Li take part in the interpretation of data. All authors have read and approved the manuscript.
The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Institutional Review Board of the Zigong Medical Foundation (IRB number: 20191001) and the Psychiatric Hospital of Ziyang (IRB number: zjsjsbyy-kyxm-2019-2). All participants or their legal guardians provided written informed consent. All methods were consistent with relevant guidelines and regulations.
Not applicable.
The authors declare that there are no conflicts of interest.
Not applicable.