Does An Association Exist Between A PSG Parameter and Cardiovascular Risks?

We aimed to ascertain polysomnography-related parameters of OSA (Obstructive Sleep Apnea) other than AHI which show an association with cardiovascular risks and co-morbidity burden. The data of 60 OSA patients who had undergone Polysomnography(PSG) was evaluated for total sleep time (TST), sleep efficiency, PLMS-I (periodic limb movement of sleep Index), Wake after sleep onset (WASO), %rapid eye movement (REM) sleep, mean duration of apnea and hypopnea, minimum peripheral oxygen saturation, lowest and highest heart rate during sleep to identify their association with co-existent cardiovascular risk and co-morbidity burden in terms of Framingham Risk Score(FRS) and Charlson Comorbidity Index(CCI). We found that amongst evaluated parameters of PSG only PLMS-I of ≥15/hour showed a weak but positive correlation with (r=0.302, p=0.023) FRS and CCI (r=0.346, p=0.007). The recruited cases of OSA were then further divided into two groups based on PLMS-I. On cross sectional examination it was observed that the group with PLMS index ≥15/hour were of higher mean age 53.29 ± 15.19 years as compared to 42.16 ± 14.3 years for the group with PLMS-I <15/hr and had a significantly higher percentage (76.7%) of co-existent Hypertension as compared to 23.3% in the group with PLMS-I <15/hr (p value=0.026). Both the groups were similar in all other features including AHI, gender composition, BMI, Epworth sleepiness scale and other PSG parameters (p value >0.05). Hence, we must give special attention to PLMS index while evaluating OSA patients as this can bring a paradigm shift in current AHI-based management of OSA which will ultimately lead us to development of a phenotype-based individualized treatment of OSA in future.