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Table 2 Significant risk factors associated with MCAT and the results of bias risk assessment

From: Assessment of the risks of a myasthenic crisis after thymectomy in patients with myasthenia gravis: a systematic review and meta-analysis of 25 studies

Significant Risk Factors   No. of studies No. of MC No. of total patients Analysis model Adjusted OR (95%CI) Study heterogeneity Test for overall effect Begg’s test P value
        Q P I2,% Z P value  
Preoperative patient condition-related risk factors
 Preoperative MC history   12 377 2094 Fixed 4.13 [3.08, 5.54] 13.46 0.26 18 9.46 <0.00001 0.034
without ref           
with            
 Preoperative bulbar symptoms   8 254 1443 Fixed 3.71 [2.54, 5.42] 7.55 0.37 7 6.76 <0.00001 0.174
without ref           
with            
 Preoperative Osserman stages   10 358 2040 Fixed 4.55 [3.23, 6.13] 30.74 0.0006 67 9.15 <0.00001 0.64
I ref           
IIa + IIb + III + VI 2     2.57 [1.43,4.61] 0.01 0.94 0 3.16 0.002  
IIb + III + VI 8     11.15 [6.88,18.08] 5.41 0.61 0 9.78 <0.00001  
VI + V 1     1.80 [0.96, 3.36] NA NA NA 1.84 0.002  
 Postoperative lung infection   5 92 448 Fixed 6.49 [2.64, 15.98] 2.39 0.5 0 4.07 <0.00001 0.624
without ref           
with            
 Thymoma   5 234 1390 Fixed 2.96 [2.13, 4.13] 3.63 0.3 17 6.43 <0.00001 0.806
no ref           
yes            
 Preoperative dosage of pyridostigmine bromide   4 193 1103 Fixed 3.53 [2.47,5.03] 4.98 0.17 40 6.94 <0.00001 1
≥240 mg            
<240 mg ref           
 Preoperative serum AchR-Ab level (nm/L)   2 27 248 Fixed 8.74 [3.31, 23.08] 0.03 0.87 0 3.65 0.0003 1
>100            
≤100 ref           
 Operation time   3 95 325 Random 1.18 [0.89, 1.57] 19.47 <0.00001 90 1.13 0.26 0.296
Surgery-related risk factors
 Intraoperative blood loss > 1000 ml   2 26 185 Fixed 15.03 [3.50, 64.50] 0.03 0.87 0 3.65 0.0003 1
>1000 ml            
≤1000 ml ref           
 WHO classification   2 25 190 Fixed 15.23 [4.63, 50.13] 0.22 0.64 0 4.48 <0.00001 1
non-thymoma and non-invasive thymoma ref           
invasive thymoma            
 Mode of operation   4 66 252 Fixed 5.88 [2.06,16.80] 2.09 0.55 0 3.3 0.001 0.089
video-assisted thoracoscopy ref           
thoracotomy            
Postoperative risk factors
 Preoperative lung function   5 110 784 Fixed 5.71 [3.11, 10.48] 3.3 0.51 0 5.62 <0.00001 1
normal ref           
abnormal            
 Major postoperative complications   3 87 391 Fixed 33.78 [10.57,107.96] 1.59 0.45 0 5.94 <0.00001 1
without ref           
with            
 Disease duration before thymectomy   2 39 452 Fixed 5.45 [1.96, 15.14] 0.02 0.9 0 3.26 0.001 1
   1983 11,345