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Valid measures of periodic leg movements (PLMs) during a suggested immobilization test using the PAM-RL leg activity monitors require adjusting detection parameters for noise and signal in each recording.
Sleep Med. 2014 Jan; 15(1):132-7.SM

Abstract

OBJECTIVE AND BACKGROUND

Individuals with restless legs syndrome (RLS) (Willis-Ekbom disease [WED]) usually have periodic leg movements (PLMs). The suggested immobilization test (SIT) measures sensory and motor features of WED during wakefulness. Surface electromyogram (EMG) recordings of the anterior tibialis (AT) are used as the standard for counting PLMs. However, due to several limitations, leg activity meters such as the PAM-RL were advanced as a potential substitute. In our study, we assessed the validity of the measurements of PLM during wakefulness (PLMW) in the SIT for PAM-RL using both default and custom detection threshold parameters compared to AT EMG.

METHODS

Data were obtained from 39 participants who were diagnosed with primary WED and who were on stable medication as part of another study using the SIT to repeatedly evaluate WED symptoms over 6-12 months. EMG recordings and PAM-RL, when available, were used to detect PLMW for each SIT. Complete PAM-RL and polysomnography (PSG) EMG data were available for 253 SITs from that study. The default PAM-RL (dPAM-RL) detected leg movements based on manufacturer's noise (resting) and signal (movement) amplitude criteria developed to accurately detect PLM during sleep (PLMS). The custom PAM-RL (cPAM-RL) similarly detected leg movements except the noise and movement detection parameters were adjusted to match the PAM-RL data for each SIT.

RESULTS

The distributions of the differences between either dPAM-RL or cPAM-RL and EMG PLMW were strongly leptokurtic (Kurtosis >2) with many small differences and a few unusually large differences. These distributions are better described by median and quartile ranges than mean and standard deviation. Despite an adequate correlation (r=0.66) between the dPAM-RL and EMG recordings, the dPAM-RL on average significantly underscored the number of PLMW (median: quartiles=-13: -51.2, 0.0) and on Bland-Altman plots had a significant magnitude bias with greater underscoring for larger average PLMW/h. There also was an adequate correlation (r=0.70) between cPAM-RL and EMG but with minimal underscoring of PLMW (median quartiles=0.0; -20, 10) and no significant magnitude bias. Two scorers independently scoring 13% of the SITs showed an adequate interscorer reliability of 0.96-0.98.

CONCLUSIONS

Our study confirms our expectation that measuring PLMW in a SIT using dPAM-RL is not valid and that adjustments to the detection threshold criteria are required. The PAM-RL, using parameters customized for each SIT provided a valid and reliable measure of PLMW with minimal magnitude bias compared to the AT EMG recordings.

Authors+Show Affiliations

Johns Hopkins University, 5501 Hopkins Bayview Circle, 1B.70, Baltimore, MD 21224, USA.Université de Montréal, Hôpital du Sacré-Coeur de Montréal, 5400 Boulevard Gouin Ouest Montréal, Québec H4J 1C5, Canada.Université de Montréal, Hôpital du Sacré-Coeur de Montréal, 5400 Boulevard Gouin Ouest Montréal, Québec H4J 1C5, Canada.Harvard Medical School, 1505 Commonwealth Ave 5th Floor, Brighton, MA 02135, USA.University of Minnesota, 425 E River Rd, Minneapolis, MN 55455, USA.Johns Hopkins University, 5501 Hopkins Bayview Circle, 1B.82, Baltimore, MD 21224, USA.Johns Hopkins University, 5501 Hopkins Bayview Circle, 1B.70, Baltimore, MD 21224, USA. Electronic address: richardjhu@mac.com.

Pub Type(s)

Clinical Trial
Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Validation Study

Language

eng

PubMed ID

24332046

Citation

Yang, Myung Sung, et al. "Valid Measures of Periodic Leg Movements (PLMs) During a Suggested Immobilization Test Using the PAM-RL Leg Activity Monitors Require Adjusting Detection Parameters for Noise and Signal in Each Recording." Sleep Medicine, vol. 15, no. 1, 2014, pp. 132-7.
Yang MS, Montplaisir J, Desautels A, et al. Valid measures of periodic leg movements (PLMs) during a suggested immobilization test using the PAM-RL leg activity monitors require adjusting detection parameters for noise and signal in each recording. Sleep Med. 2014;15(1):132-7.
Yang, M. S., Montplaisir, J., Desautels, A., Winkelman, J. W., Cramer Bornemann, M. A., Earley, C. J., & Allen, R. P. (2014). Valid measures of periodic leg movements (PLMs) during a suggested immobilization test using the PAM-RL leg activity monitors require adjusting detection parameters for noise and signal in each recording. Sleep Medicine, 15(1), 132-7. https://doi.org/10.1016/j.sleep.2013.08.788
Yang MS, et al. Valid Measures of Periodic Leg Movements (PLMs) During a Suggested Immobilization Test Using the PAM-RL Leg Activity Monitors Require Adjusting Detection Parameters for Noise and Signal in Each Recording. Sleep Med. 2014;15(1):132-7. PubMed PMID: 24332046.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Valid measures of periodic leg movements (PLMs) during a suggested immobilization test using the PAM-RL leg activity monitors require adjusting detection parameters for noise and signal in each recording. AU - Yang,Myung Sung, AU - Montplaisir,Jacques, AU - Desautels,Alex, AU - Winkelman,John W, AU - Cramer Bornemann,Michel A, AU - Earley,Christopher J, AU - Allen,Richard P, Y1 - 2013/10/16/ PY - 2013/04/08/received PY - 2013/08/26/revised PY - 2013/08/30/accepted PY - 2013/12/17/entrez PY - 2013/12/18/pubmed PY - 2014/9/24/medline KW - Leg activity monitors KW - PAM-RL KW - Periodic leg movements during wakefulness (PLMW) KW - Polysomnography KW - Restless Legs Syndrome (RLS) KW - Suggested immobilization test (SIT) KW - Willis Ekbom disease (WED) SP - 132 EP - 7 JF - Sleep medicine JO - Sleep Med VL - 15 IS - 1 N2 - OBJECTIVE AND BACKGROUND: Individuals with restless legs syndrome (RLS) (Willis-Ekbom disease [WED]) usually have periodic leg movements (PLMs). The suggested immobilization test (SIT) measures sensory and motor features of WED during wakefulness. Surface electromyogram (EMG) recordings of the anterior tibialis (AT) are used as the standard for counting PLMs. However, due to several limitations, leg activity meters such as the PAM-RL were advanced as a potential substitute. In our study, we assessed the validity of the measurements of PLM during wakefulness (PLMW) in the SIT for PAM-RL using both default and custom detection threshold parameters compared to AT EMG. METHODS: Data were obtained from 39 participants who were diagnosed with primary WED and who were on stable medication as part of another study using the SIT to repeatedly evaluate WED symptoms over 6-12 months. EMG recordings and PAM-RL, when available, were used to detect PLMW for each SIT. Complete PAM-RL and polysomnography (PSG) EMG data were available for 253 SITs from that study. The default PAM-RL (dPAM-RL) detected leg movements based on manufacturer's noise (resting) and signal (movement) amplitude criteria developed to accurately detect PLM during sleep (PLMS). The custom PAM-RL (cPAM-RL) similarly detected leg movements except the noise and movement detection parameters were adjusted to match the PAM-RL data for each SIT. RESULTS: The distributions of the differences between either dPAM-RL or cPAM-RL and EMG PLMW were strongly leptokurtic (Kurtosis >2) with many small differences and a few unusually large differences. These distributions are better described by median and quartile ranges than mean and standard deviation. Despite an adequate correlation (r=0.66) between the dPAM-RL and EMG recordings, the dPAM-RL on average significantly underscored the number of PLMW (median: quartiles=-13: -51.2, 0.0) and on Bland-Altman plots had a significant magnitude bias with greater underscoring for larger average PLMW/h. There also was an adequate correlation (r=0.70) between cPAM-RL and EMG but with minimal underscoring of PLMW (median quartiles=0.0; -20, 10) and no significant magnitude bias. Two scorers independently scoring 13% of the SITs showed an adequate interscorer reliability of 0.96-0.98. CONCLUSIONS: Our study confirms our expectation that measuring PLMW in a SIT using dPAM-RL is not valid and that adjustments to the detection threshold criteria are required. The PAM-RL, using parameters customized for each SIT provided a valid and reliable measure of PLMW with minimal magnitude bias compared to the AT EMG recordings. SN - 1878-5506 UR - https://www.unboundmedicine.com/medline/citation/24332046/Valid_measures_of_periodic_leg_movements__PLMs__during_a_suggested_immobilization_test_using_the_PAM_RL_leg_activity_monitors_require_adjusting_detection_parameters_for_noise_and_signal_in_each_recording_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1389-9457(13)01156-8 DB - PRIME DP - Unbound Medicine ER -