Sleep Breath DOI 10.1007/s11325-014-0999-4
LETTER TO THE EDITORS
Response to letter on “Validation study on sleep parameters by actigraphy for normal subjects” Conor Heneghan
Received: 14 April 2014 / Accepted: 30 April 2014 # Springer-Verlag Berlin Heidelberg 2014
Dear Editor: We thank Dr. Kawada for his comment on our work [1] as he raises an important point in relation to the use of actigraphy in sleep assessment, namely, that the optimal Actiwatch setting for maximizing sleep/wake accuracy will be subjectdependent. As noted in our paper, we used the “default” settings for Actiwatch sensitivity provided by the manufacturer, which resulted in an overall accuracy that was comparable to the other instruments in the study, but which had lower wake specificity. It would have been helpful to have also included the results when the “high sensitivity” setting was used, which has the tendency to increase wake specificity at the expense of sleep sensitivity. In a related publication [2] where we reported on the results of Actiwatch and biomotion sensor in a sleep apnea population, the Actiwatch sleep sensitivity and wake specificity were 0.94 and 0.34 at the default setting, but changed to 0.90 and 0.45 at the high sensitivity setting. These findings are consistent with Kushida’s results at “high sensitivity” setting which gave 0.92 and 0.48 for the corresponding measures [3]. In short, we agree with Dr. Kawada’s commentary that researchers need to be aware of the impact of the actigraphy algorithm sensitivity settings on the results, and that in subjects with a high pre-test probability of wakefulness, one
C. Heneghan (*) ResMed Sensor Technologies, Belfield Office Park, Clonskeagh, Dublin 4, Ireland e-mail: [email protected]
should consider the use of the “high sensitivity” settings in addition to the default setting. We also agree that further studies in clinically interesting populations such as those with sleep disordered breathing, periodic limb movements and primary insomnia should be carried out to validate the use of non-PSG sleep measurement devices. Disclosure Conor Heneghan is an employee of ResMed, a manufacturer of sleep apnea therapy and diagnostic equipment.
References 1. O'Hare E, Flanagan D, Penzel T, Garcia C, Frohberg D, Heneghan C (2014) A comparison of radio-frequency biomotion sensors and actigraphy versus polysomnography for the assessment of sleep in normal subjects. Sleep Breath. doi:10.1007/s11325-014-0967-z 2. Pallin M, O'Hare E, Zaffaroni A, Boyle P, Fagan C, Kent B, Heneghan C, de Chazal P and McNicholas WT (2014) Comparison of a novel non-contact biomotion sensor with wrist actigraphy in estimating sleep quality in patients with obstructive sleep apnoea. J. Sleep Research, Feb 3. doi:10.1111/jsr.12126 3. Kushida CA, Chang A, Gadkary C, Guilleminault C, Carrillo O, Dement WC (2001) Comparison of actigraphic, polysomnographic, and subjective assessment of sleep parameters in sleep-disordered patients. Sleep Med 2(5):389–396
LETTER TO THE EDITORS
Response to letter on “Validation study on sleep parameters by actigraphy for normal subjects” Conor Heneghan
Received: 14 April 2014 / Accepted: 30 April 2014 # Springer-Verlag Berlin Heidelberg 2014
Dear Editor: We thank Dr. Kawada for his comment on our work [1] as he raises an important point in relation to the use of actigraphy in sleep assessment, namely, that the optimal Actiwatch setting for maximizing sleep/wake accuracy will be subjectdependent. As noted in our paper, we used the “default” settings for Actiwatch sensitivity provided by the manufacturer, which resulted in an overall accuracy that was comparable to the other instruments in the study, but which had lower wake specificity. It would have been helpful to have also included the results when the “high sensitivity” setting was used, which has the tendency to increase wake specificity at the expense of sleep sensitivity. In a related publication [2] where we reported on the results of Actiwatch and biomotion sensor in a sleep apnea population, the Actiwatch sleep sensitivity and wake specificity were 0.94 and 0.34 at the default setting, but changed to 0.90 and 0.45 at the high sensitivity setting. These findings are consistent with Kushida’s results at “high sensitivity” setting which gave 0.92 and 0.48 for the corresponding measures [3]. In short, we agree with Dr. Kawada’s commentary that researchers need to be aware of the impact of the actigraphy algorithm sensitivity settings on the results, and that in subjects with a high pre-test probability of wakefulness, one
C. Heneghan (*) ResMed Sensor Technologies, Belfield Office Park, Clonskeagh, Dublin 4, Ireland e-mail: [email protected]
should consider the use of the “high sensitivity” settings in addition to the default setting. We also agree that further studies in clinically interesting populations such as those with sleep disordered breathing, periodic limb movements and primary insomnia should be carried out to validate the use of non-PSG sleep measurement devices. Disclosure Conor Heneghan is an employee of ResMed, a manufacturer of sleep apnea therapy and diagnostic equipment.
References 1. O'Hare E, Flanagan D, Penzel T, Garcia C, Frohberg D, Heneghan C (2014) A comparison of radio-frequency biomotion sensors and actigraphy versus polysomnography for the assessment of sleep in normal subjects. Sleep Breath. doi:10.1007/s11325-014-0967-z 2. Pallin M, O'Hare E, Zaffaroni A, Boyle P, Fagan C, Kent B, Heneghan C, de Chazal P and McNicholas WT (2014) Comparison of a novel non-contact biomotion sensor with wrist actigraphy in estimating sleep quality in patients with obstructive sleep apnoea. J. Sleep Research, Feb 3. doi:10.1111/jsr.12126 3. Kushida CA, Chang A, Gadkary C, Guilleminault C, Carrillo O, Dement WC (2001) Comparison of actigraphic, polysomnographic, and subjective assessment of sleep parameters in sleep-disordered patients. Sleep Med 2(5):389–396
