PMID- 33067835
OWN - NLM
STAT- MEDLINE
DCOM- 20210315
LR  - 20210315
IS  - 1097-4598 (Electronic)
IS  - 0148-639X (Linking)
VI  - 63
IP  - 2
DP  - 2021 Feb
TI  - Identifying jitter outliers in single fiber electromyography: Comparison of four 
      methods.
PG  - 217-224
LID - 10.1002/mus.27093 [doi]
AB  - BACKGROUND: Little is known about how different outlier estimation methods affect 
      cutoff limits for outliers in single fiber electromyography. METHODS: We compared 
      in a prospective fashion the established 18th jitter value (18thjv) method to 
      three, whole-distribution based, outlier detection methods: the interquartile 
      range (IQR), the log-normal, and the Z-score method. The reference limits were 
      probed in a normal cohort and in myasthenia gravis (MG) patients. RESULTS: 
      Differences in outlier cutoff values between the different methods were in the 
      range of 2 mus. The number of abnormal muscles according to the computed criteria 
      was similar for all four methods in the control group. Classification metrics 
      (sensitivity, specificity, Youden's statistic, and predictive values) were also 
      similar among the different methods. In the MG group, however, the Z-score method 
      failed to identify the abnormal jitter values. Accordingly, Kappa agreement was 
      substantial to perfect (0.658 to 1) between the three methods (18thjv, IQR, and 
      log-normal), but was equivalent to chance between the three methods and the 
      Z-score in the MG group. CONCLUSIONS: The established 18thjv method proved 
      largely robust when compared to whole-distribution based methods, and its use in 
      clinical practice is justified. Simple estimation of outlier limits by adding two 
      SDs to the mean of the data, leads to unacceptable deviations from the true 
      cutoff values. Moreover, in a clinical scenario in which the final 
      electrodiagnosis depends only on the number of outliers, it is meaningful to 
      accept a tolerance zone of about 2 mus, which is the approximate variation range 
      among the different methods.
CI  - (c) 2020 Wiley Periodicals LLC.
FAU - Anagnostou, Evangelos
AU  - Anagnostou E
AD  - Department of Neurology, University of Athens, Eginition Hospital, Athens, 
      Greece.
FAU - Dimopoulou, Panagiota
AU  - Dimopoulou P
AD  - Department of Neurology, University of Athens, Eginition Hospital, Athens, 
      Greece.
FAU - Sklavos, Sokratis
AU  - Sklavos S
AD  - Department of Neurology, University of Athens, Eginition Hospital, Athens, 
      Greece.
FAU - Zouvelou, Vasiliki
AU  - Zouvelou V
AD  - Department of Neurology, University of Athens, Eginition Hospital, Athens, 
      Greece.
FAU - Zambelis, Thomas
AU  - Zambelis T
AD  - Department of Neurology, University of Athens, Eginition Hospital, Athens, 
      Greece.
LA  - eng
PT  - Comparative Study
PT  - Journal Article
DEP - 20201026
PL  - United States
TA  - Muscle Nerve
JT  - Muscle & nerve
JID - 7803146
SB  - IM
MH  - Adolescent
MH  - Adult
MH  - Aged
MH  - Aged, 80 and over
MH  - Case-Control Studies
MH  - Electromyography/*methods
MH  - Facial Muscles/*physiology/physiopathology
MH  - Female
MH  - Forearm
MH  - Healthy Volunteers
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Muscle Fibers, Skeletal/*physiology
MH  - Muscle, Skeletal/physiology/physiopathology
MH  - Myasthenia Gravis/*physiopathology
MH  - Reference Values
MH  - Young Adult
OTO - NOTNLM
OT  - jitter
OT  - outliers
OT  - reference values
OT  - single fiber electromyography
OT  - skewed distribution
EDAT- 2020/10/18 06:00
MHDA- 2021/03/16 06:00
CRDT- 2020/10/17 05:31
PHST- 2020/04/22 00:00 [received]
PHST- 2020/10/06 00:00 [revised]
PHST- 2020/10/10 00:00 [accepted]
PHST- 2020/10/18 06:00 [pubmed]
PHST- 2021/03/16 06:00 [medline]
PHST- 2020/10/17 05:31 [entrez]
AID - 10.1002/mus.27093 [doi]
PST - ppublish
SO  - Muscle Nerve. 2021 Feb;63(2):217-224. doi: 10.1002/mus.27093. Epub 2020 Oct 26.