Is There a Clinical Role For Smartphone Sleep Apps? Comparison of Sleep Cycle Detection by a Smartphone Application to Polysomnography.

STUDY OBJECTIVES: Several inexpensive, readily available smartphone apps that claim to monitor sleep are popular among patients. However, their accuracy is unknown, which limits their widespread clinical use. We therefore conducted this study to evaluate the validity of parameters reported by one such app, the Sleep Time app (Azumio, Inc., Palo Alto, CA, USA) for iPhones. METHODS: Twenty volunteers with no previously diagnosed sleep disorders underwent in-laboratory polysomnography (PSG) while simultaneously using the app. Parameters reported by the app were then compared to those obtained by PSG. In addition, an epoch-by-epoch analysis was performed by dividing the PSG and app graph into 15-min epochs. RESULTS: There was no correlation between PSG and app sleep efficiency (r = -0.127, p = 0.592), light sleep percentage (r = 0.024, p = 0.921), deep sleep percentage (r = 0.181, p = 0.444) or sleep latency (rs = 0.384, p = 0.094). The app slightly and nonsignificantly overestimated sleep efficiency by 0.12% (95% confidence interval [CI] -4.9 to 5.1%, p = 0.962), significantly underestimated light sleep by 27.9% (95% CI 19.4-36.4%, p < 0.0001), significantly overestimated deep sleep by 11.1% (CI 4.7-17.4%, p = 0.008) and significantly overestimated sleep latency by 15.6 min (CI 9.7-21.6, p < 0.0001). Epochwise comparison showed low overall accuracy (45.9%) due to poor interstage discrimination, but high accuracy in sleep-wake detection (85.9%). The app had high sensitivity but poor specificity in detecting sleep (89.9% and 50%, respectively). CONCLUSIONS: Our study shows that the absolute parameters and sleep staging reported by the Sleep Time app (Azumio, Inc.) for iPhones correlate poorly with PSG. Further studies comparing app sleep-wake detection to actigraphy may help elucidate its potential clinical utility. COMMENTARY: A commentary on this article appears in this issue on page 695.

Usefulness of clopidogrel to protect against diabetes-induced vascular damage.

Clopidogrel enhances the levels of endothelial nitric oxide and prostacyclin in tissue culture. We have previously described a marked increase in circulating endothelial cells (CECs), an ex vivo indicator of vascular injury, in patients with type 2 diabetes mellitus. We hypothesized that clopidogrel treatment would result in a decrease in CEC number and increased activity of endothelial progenitor cell recruitment signaling pathways in diabetic patients. CECs were isolated from the peripheral blood of 9 patients with type 2 diabetes using anti-CD146-coated Dynabeads. The cells were stained with acridine orange and counted by fluorescence microscopy. Endothelial progenitor cells were isolated in a similar fashion using anti-CD34 and anti-CD133 and assayed for expression of phosphorylated Akt and phosphorylated adenosine monophosphate kinase. The patients were then treated with clopidogrel 75 mg/day for 30 days, after which repeat blood specimens were analyzed. As previously observed, diabetic patients had an elevated number of CECs (mean 79 +/- 15 cells/ml peripheral blood), which was reduced by clopidogrel treatment (mean 10 +/- 4 cells/ml; p <0.001). This was associated with a significant increase in the expression of both phosphorylated Akt and phosphorylated adenosine monophosphate kinase (p

Interhospital transfer of patients with ST-segment elevation myocardial infarction for percutaneous coronary intervention.

We investigated in 277 consecutive patients, mean age 63 years, with ST-segment elevation acute myocardial infarction transferred from 25 community hospitals to a tertiary percutaneous coronary intervention (PCI) center from a median distance of 21 miles the incidences of in-hospital mortality, stroke, and recurrent myocardial infarction associated with transfer times. Of the 277 patients, 158 (57%) had thrombolytic therapy at the referring hospital. Of the 277 patients, 63 (23%) had adjunctive PCI, 119 (43%) had primary PCI, and 95 (34%) had rescue PCI. Of the 277 patients, 42 (15%) were hemodynamically unstable. Median transfer times were 102 minutes with primary PCI, 119 minutes with rescue PCI, and 144 minutes for adjunctive PCI (P < 0.0001 for adjunctive PCI versus primary PCI; P = 0.011 for adjunctive PCI versus rescue PCI). Median transfer time was 98 minutes for hemodynamically unstable patients and 121 minutes for hemodynamically stable patients (P = 0.005). In-hospital death occurred in eight of 277 patients (3%). In-hospital stroke occurred in three of 277 patients (1%). In-hospital recurrent myocardial infarction occurred in none of 277 patients (0%). There was no association of transfer times with in-hospital mortality or stroke. In-hospital mortality occurred in three of 112 patients (3%) who had bare metal stents and in five of 165 patients (3%) who had drug-eluting stents.