TY - JOUR
T1 - Putting the periodicity back into the periodic leg movement index
T2 - An alternative data-driven algorithm for the computation of this index during sleep and wakefulness
AU - Ferri, Raffaele
AU - Rundo, Francesco
AU - Zucconi, Marco
AU - Manconi, Mauro
AU - Aricò, Debora
AU - Bruni, Oliviero
AU - Ferini-Strambi, Luigi
AU - Fulda, Stephany
PY - 2015/10/1
Y1 - 2015/10/1
N2 - Objective: To evaluate an alternative index for periodic leg movements during sleep (PLMS) and wakefulness (PLMW) expected to be similar to the standard index when leg movement activity is genuinely periodic, but significantly lower when periodicity is low. Subjects and methods: One-hundred-and-seven subjects with restless legs syndrome (RLS) were retrospectively identified and included (47 males, 60 females, mean age 56.9 years), along with 63 controls (33 males, 30 females, 42.2 years). Night-to-night variability was analysed in a subgroup of 17 subjects with RLS. PLMW were evaluated in a subgroup of 66 RLS subjects. Two 'alternative' PLMS/PLMW indices were calculated: one increased the lower limit of the inter-movement intervals from 5 to 10 s ('Alt1') and another additionally considered only series not interrupted by LMs with a short inter-movement interval ('Alt2'). Results: Despite a high correlation between methods, only the Alt2 algorithm provided significantly different results, with PLMS/PLMW indices being consistently lower than those provided by the other two methods. The difference was more evident in the controls and during wakefulness, when periodicity was lower. The difference between the Alt2 and the standard PLMS index showed a significantly negative correlation with the Periodicity Index. Night-to-night variability was similar for all PLMS indices and significantly higher than the variability seen in the Periodicity Index. Conclusion: This methodological study introduces an alternative to the standard PLMS/PLMW indices, initiating the validation process for a new way of computing the PLMS/PLMW index, more adherent to the parameters that allows a reliable evaluation of their periodicity.
AB - Objective: To evaluate an alternative index for periodic leg movements during sleep (PLMS) and wakefulness (PLMW) expected to be similar to the standard index when leg movement activity is genuinely periodic, but significantly lower when periodicity is low. Subjects and methods: One-hundred-and-seven subjects with restless legs syndrome (RLS) were retrospectively identified and included (47 males, 60 females, mean age 56.9 years), along with 63 controls (33 males, 30 females, 42.2 years). Night-to-night variability was analysed in a subgroup of 17 subjects with RLS. PLMW were evaluated in a subgroup of 66 RLS subjects. Two 'alternative' PLMS/PLMW indices were calculated: one increased the lower limit of the inter-movement intervals from 5 to 10 s ('Alt1') and another additionally considered only series not interrupted by LMs with a short inter-movement interval ('Alt2'). Results: Despite a high correlation between methods, only the Alt2 algorithm provided significantly different results, with PLMS/PLMW indices being consistently lower than those provided by the other two methods. The difference was more evident in the controls and during wakefulness, when periodicity was lower. The difference between the Alt2 and the standard PLMS index showed a significantly negative correlation with the Periodicity Index. Night-to-night variability was similar for all PLMS indices and significantly higher than the variability seen in the Periodicity Index. Conclusion: This methodological study introduces an alternative to the standard PLMS/PLMW indices, initiating the validation process for a new way of computing the PLMS/PLMW index, more adherent to the parameters that allows a reliable evaluation of their periodicity.
KW - Index
KW - Periodic leg movements during sleep
KW - PLMS
KW - PLMW
KW - Restless legs syndrome
KW - Sleep scoring
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U2 - 10.1016/j.sleep.2015.05.019
DO - 10.1016/j.sleep.2015.05.019
M3 - Article
C2 - 26429751
AN - SCOPUS:84942521549
VL - 16
SP - 1229
EP - 1235
JO - Sleep Medicine
JF - Sleep Medicine
SN - 1389-9457
IS - 10
ER -