Effectiveness of home single-channel nasal pressure for sleep apnea diagnosis

Abstract

Introduction: Home single-channel nasal pressure (HNP) may be an alternative to polysomnography (PSG) for obstructive sleep apnea (OSA) diagnosis, but no cost studies have yet been carried out. Automatic scoring is simpler but generally less effective than manual scoring.

Objectives: To determine the diagnostic efficacy and cost of both scorings (automatic and manual) compared with PSG, taking as a polysomnographic OSA diagnosis several apnea-hypopnea index (AHI) cutoff points.

Methods: We included suspected OSA patients in a multicenter study. They were randomized to home and hospital protocols. We constructed receiver operating characteristic (ROC) curves for both scorings. Diagnostic efficacy was explored for several HNP AHI cutoff points, and costs were calculated for equally effective alternatives.

Results: Of 787 randomized patients, 752 underwent HNP. Manual scoring produced better ROC curves than automatic for AHI < 15; similar curves were obtained for AHI ≥ 15. A valid HNP with manual scoring would determine the presence of OSA (or otherwise) in 90% of patients with a polysomnographic AHI ≥ 5 cutoff point, in 74% of patients with a polysomnographic AHI ≥ 10 cutoff point, and in 61% of patients with a polysomnographic AHI ≥ 15 cutoff point. In the same way, a valid HNP with automatic scoring would determine the presence of OSA (or otherwise) in 73% of patients with a polysomnographic AHI ≥ 5 cutoff point, in 64% of patients with a polysomnographic AHI ≥ 10 cutoff point, and in 57% of patients with a polysomnographic AHI ≥ 15 cutoff point. The costs of either HNP approaches were 40% to 70% lower than those of PSG at the same level of diagnostic efficacy. Manual HNP had the lowest cost for low polysomnographic AHI levels (≥ 5 and ≥ 10), and manual and automatic scorings had similar costs for higher polysomnographic cutoff points (AHI ≥ 15) of diagnosis.

Conclusion: Home single-channel nasal pressure (HNP) is a cheaper alternative than polysomnography for obstructive sleep apnea diagnosis. HNP with manual scoring seems to have better diagnostic accuracy and a lower cost than automatic scoring for patients with low apnea-hypopnea index (AHI) levels, although automatic scoring has similar diagnostic accuracy and cost as manual scoring for intermediate and high AHI levels. Therefore, automatic scoring can be appropriately used, although diagnostic efficacy could improve if we carried out manual scoring on patients with AHI < 15.

Clinical trials information: Clinicaltrials.gov identifier: NCT01347398.

Keywords: Apnealink; cost-effectiveness; portable monitor; sleep apnea.

Figure 1

Example of a manual home single-channel nasal pressure scoring by ApneaLink software (version 6.01) in a patient with obstructive sleep apnea. Red color shows apneas and blue color hypopneas on nasal pressure channel.

Figure 2

(A) Of 787 patients randomized, 34 were lost without any additional costs. Of 753 who underwent PSG, 749 had valid recordings (99%) after 21 repetitions, with 4 invalid recordings where an additional PSG cost was included. (B) PSG AHI ≥ 5: Of 787 patients randomized, 35 were lost without any additional costs. Of 752 patients who underwent HNP, 76 recordings had to be repeated, with the subsequent repetition costs. Of these 752 patients, 662 had valid and 90 invalid manual recordings (88% and 12%, respectively). An additional PSG cost was included for invalid recordings. Of the 662 subjects with valid manual HNP recordings, 29 patients had a true negative result (no OSA) and 525 had a true positive result (OSA). Seventy-five patients had no positive or negative diagnosis of OSA (gray zone), 11 false positives, and 22 negatives, and a PSG cost was added to them. Of 752 patients, 595 had valid and 157 invalid automatic recordings (79% and 21%, respectively). An additional PSG cost was included for invalid recordings. Of the 595 subjects with valid automatic HNP recordings, there were 432 with a true positive result (OSA) and no patients with a true negative result. There were 154 patients with no positive or negative diagnosis of OSA (gray zone) and 9 false positives and a PSG cost was added to them. (C) PSG AHI ≥ 10: Of the 662 subjects with valid manual HNP recordings, 37 patients had a true negative result (no OSA) and 454 with a true positive result (OSA). One hundred thirty-seven patients had no positive or negative diagnosis of OSA (gray zone), 20 false positives, and 14 negatives, and a PSG cost was added to them. Of 752 patients, 595 had valid and 157 invalid automatic recordings (79% and 21%, respectively). An additional PSG cost was included for invalid recordings. Of the 595 subjects with valid automatic HNP recordings, 383 had a true positive result (OSA) and no patients had a true negative result. Two hundred patients had no positive or negative diagnosis of OSA (gray zone) and 12 false positives, and a PSG cost was added to them. (D) PSG AHI ≥ 15: Of the 662 subjects with valid manual HNP recordings, 42 patients had a true negative result (no OSA) and 361 with a true positive result (OSA). Two hundred thirty-five patients had no positive or negative diagnosis of OSA (gray zone), 15 false positives, and 9 negatives, and a PSG cost was added to them. Of 752 patients, 595 had valid and 157 invalid automatic recordings (79% and 21%, respectively). An additional PSG cost was included for invalid recordings. Of the 595 subjects with valid automatic HNP recordings, there were 337 with a true positive result (OSA) and no patients with a true negative result. There were 246 patients with no positive or negative diagnosis of OSA (gray zone), and 12 false positives and a PSG cost was added to them. PSG, polysomnography; HNP, home single-channel nasal pressure; OSA, obstructive sleep apnea.

Figure 3

AUCs from receiver operating characteristics (ROC) curves for the manual and automatic HNP scorings, based on AHI polysomnographic cutoff points for sleep apnea diagnosis from ≥ 5 to ≥ 30. PSG, polysomnography; AUC, area under the curve; HNP, home single-channel nasal pressure; AHI, apnea-hypopnea index; CI, confidence interval

Figure 4

Percentages of total HNP costs for manual and automatic scorings (PSG AHI ≥ 5 and ≥ 15 cutoff points of OSA diagnosis) and their distribution in three groups (test cost, patients' cost and cost for equal efficacy) compared to polysomnography costs, which were considered to be 100% of the total cost. HNP, home single-channel nasal pressure; PSG, polysomnography; OSA, obstructive sleep apnea.