High-resolution wrist-worn overnight oximetry has high positive predictive value for obstructive sleep apnea in a sleep study referral population.

BACKGROUND: Reducing the need for diagnostic sleep studies for obstructive sleep apnea (OSA) would reduce direct and opportunity costs while expediting time to treatment for this common and morbid disorder. We sought to determine if an established sleep apnea screening questionnaire (STOP-BANG) and wrist-worn overnight oximetry data could provide high positive predictive value for the presence of OSA. METHODS: We conducted a prospective observational study of consecutive unattended sleep study patients at a single facility. Patients were referred for sleep testing after chart review by a sleep physician. We assessed area under the receiver-operating characteristic curve (ROC AUC) and positive predictive value (PPV) of STOP-BANG score and oxygen desaturation index (ODI) for a respiratory disturbance index (RDI) ≥15/h. RESULTS: Among 234 test patients, 65 % had an RDI ≥15/h. STOP-BANG had poor ability to discriminate these patients (ROC AUC 0.62). ODI added significant diagnostic information to the STOP-BANG score, increasing the ROC AUC to 0.86. Having the ODI, the STOP-BANG score no longer contributed significant diagnostic information, and the ODI alone discriminated as well as the combination (ROC AUC 0.86). Forty nine percent had an ODI ≥7/h, which had PPV of 92 % (95 % confidence interval (CI), 86 to 96 %). In the validation sample of 1,196 consecutive patients, ODI ≥ 7/h had a PPV of 97 % (95 % CI, 95 to 97 %). CONCLUSIONS: Among patients with a high prevalence of OSA, high ODI is common and its presence has high PPV for OSA. These data suggest that overnight oximetry prior to sleep testing could significantly reduce the number of patients requiring sleep studies, thereby reducing costs and time to treatment.

High-dose oral N-acetylcysteine fails to improve respiratory health status in patients with chronic obstructive pulmonary disease and chronic bronchitis: a randomized, placebo-controlled trial.

BACKGROUND: Clinical outcomes are worse in patients with COPD and chronic bronchitis. N-acetylcysteine (NAC) is commonly prescribed for such patients but with uncertain clinical benefits. We postulated that oral NAC, at much larger doses than those ordinarily prescribed, would improve clinical outcomes in a subset of patients with COPD and chronic bronchitis. OBJECTIVE: The aim of this study was to determine whether very high-dose NAC would improve respiratory health status in patients with COPD and chronic bronchitis. METHODS: Patients with COPD and chronic bronchitis were enrolled in a randomized, controlled, double-blinded trial. Patients received oral NAC (1,800 mg) or matching placebo twice daily for 8 weeks in addition to their usual respiratory medications. The primary outcome, respiratory health status, was assessed by changes in the St George's Respiratory Questionnaire. The effects of NAC on lung function and circulating markers of oxidative stress and inflammation were also evaluated. RESULTS: We terminated the study prematurely because new external information suggested the possibility of a safety issue. Of the planned 130 patients, 51 were randomized and 45 (22 in the placebo arm and 23 in the NAC arm) completed the study. There was no statistically significant difference between changes in the St George's Respiratory Questionnaire total score, comparing NAC to placebo (adjusted mean difference, 0.1 U; 95% CI, -7.8 to 8.18 U; P=0.97). There were also no significant NAC-related improvements in any of the secondary outcomes. CONCLUSION: In this 8-week trial, we were unable to show any clinical benefit from a very high dose of NAC in patients with COPD and chronic bronchitis.

Self-reported alcohol intake and risk of acute exacerbations of chronic obstructive pulmonary disease: a prospective cohort study.

OBJECTIVE: To evaluate the relationship between alcohol consumption and the risk of acute exacerbation of COPD (AECOPD). METHODS AND MEASUREMENTS: We conducted a secondary analysis of data previously collected in a large, multicenter trial of daily azithromycin in COPD. To analyze the relationship between amount of baseline self-reported alcohol consumption in the past 12 months and subsequent AECOPD, we categorized the subjects as minimal (<1 drink/month), light-to-moderate (1-60 drinks/month), or heavy alcohol users (>60 drinks/month). The primary outcome was time to first AECOPD and the secondary outcome was AECOPD rate during the 1-year study period. RESULTS: Of the 1,142 enrolled participants, 1,082 completed baseline alcohol questionnaires and were included in this analysis. Six hundred and forty-five participants reported minimal alcohol intake, 363 reported light-to-moderate intake, and 74 reported heavy intake. There were no statistically significant differences in median time to first AECOPD among minimal (195 days), light-to-moderate (241 days), and heavy drinkers (288 days) (P=0.11). The mean crude rate of AECOPD did not significantly differ between minimal (1.62 events per year) and light-to-moderate (1.44 events per year) (P=0.095), or heavy drinkers (1.68 events per year) (P=0.796). There were no significant differences in hazard ratios for AECOPD after adjustment for multiple covariates. CONCLUSION: Among persons with COPD at high risk of exacerbation, we found no significant relationship between self-reported baseline alcohol intake and subsequent exacerbations. The number of patients reporting heavy alcohol intake was small and further study is needed to determine the effect of heavy alcohol intake on AECOPD risk.

STOP-BANG questionnaire performance in a Veterans Affairs unattended sleep study program.

RATIONALE: There are no published data regarding use of the STOP-BANG sleep apnea questionnaire in populations referred to Veterans Affairs (VA) sleep facilities. If a particular STOP-BANG score cutpoint had high positive predictive value in this referral population, it could reduce the need for diagnostic sleep studies. METHODS: STOP-BANG questionnaires were prospectively administered to veterans undergoing unattended sleep studies at a single VA facility. We evaluated the sensitivity, specificity, positive predictive value, and area under the receiver-operating characteristic curve (ROC AUC) of STOP-BANG scores for identifying a Respiratory Disturbance Index (RDI) greater than 15/hour. We also recalibrated the STOP-BANG score to our referral population, using logistic regression models. MEASUREMENTS AND MAIN RESULTS: Of 1,196 consecutive veterans undergoing unattended sleep studies, the mean STOP-BANG score was 5.7 ± 1.4, and 67% had an RDI greater than 15/hour. Sensitivities were excellent at lower STOP-BANG scores, but sharply decreased at scores of 6 and above. Specificity improved in a linear fashion with increasing scores. The ROC AUC was 0.66 (95% confidence interval [CI], 0.64-0.69) and recalibrated models improved the ROC AUC to 0.74 (95% CI, 0.69-0.78). The highest STOP-BANG score of 8 was present in only 7.9% of the sample and had a positive predictive value of 85% (95% CI, 76-92%). CONCLUSIONS: The STOP-BANG questionnaire alone is insufficient to confirm the presence of significant sleep apnea. A maximal score of 8 did not have a high enough positive predictive value to forego confirmatory sleep testing.