Impact of Positive Airway Pressure Therapy on Clinical Outcomes in Older Veterans With Chronic Obstructive Pulmonary Disease and Comorbid Obstructive Sleep Apnea (Overlap Syndrome)

Trails A and Trails B test will be administered to evaluate attention and psychomotor function. This score is adjusted for age, race, gender, and years of education. Scored on a Standard scale of 100 +/- 15 for normal ranges, above 115 is above average, below 85 is considered below average.

PASAT (Paced Auditory Serial Addition Test) will be administered to evaluate vigilance and executive function. The PASAT is recorded as the total number of correct responses (from 0-60), or the percent of correct responses out of 60 (from 0-100), where a higher value is a better outcome.

Stroop color-word interference test will be administered to evaluate executive function. This score is adjusted for age, and years of education. Scored on a Standard scale of 100 +/- 15 for normal ranges, above 115 is above average, below 85 is considered below average.

DIGIT test will be administered to evaluate short-term and working memory. This score is adjusted for age. Scored on a Standard scale of 100 +/- 15 for normal ranges, above 115 is above average, below 85 is considered below average.

Abbreviated Wechsler Abbreviated Scale of Intelligence (WASI) will be administered to evaluate verbal comprehension and working memory. This score is adjusted for age. Scored on a Standard scale of 100 +/- 15 for normal ranges, above 115 is above average, below 85 is considered below average.

Wechsler Memory test (WMS) will be administered to measure Verbal comprehension, and working and visual memory. Scored on a Standard scale of 100 +/- 15, where a higher score is a better outcome.

Psychomotor Vigilance Test (PVT) will be administered to measure Alertness and vigilance, in terms of number of lapses and reaction time. The performance score ranges from 0-100, where a higher value is a better outcome.

Hopkins Verbal Learning Test - Revised (HVLT-R) will be administered to evaluate Verbal learning and memory. Scored on a Standard scale of 100 +/- 15, where a higher score is a better outcome.

Epworth sleepiness scale (ESS) score will be measured. This score is on a scale of 0-24, where a higher value indicates greater degree of sleepiness.

Pittsburgh Sleep Quality Index (PSQI) is a detailed assessment of subject sleep quality over the most recent month by considering seven "component" scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The sum of scores for these seven components yields one global score to assess sleep quality on a scale of "poor" to "good".

QoL will be assessed using the survey SF-36v2 Health survey. Thirty-five of the SF-36v2 items are used to measure eight domains of health-related quality of life. These are on a scale of 0-100, where higher values indicate a better outcome.

Disease specific QoL will be assessed using the Functional Outcomes of Sleep Questionnaire FOSQ/(FOSQ). There are 5 subscale domains of the FOSQ (General Productivity, Social Outcome, Activity Level, Vigilance, and Intimate Relationships and Sexual Activity). There all range from 0-20, where a higher value is a better outcome. The total FOSQ is the sum of these subscale domains and ranges from 0-100, where a higher value is a better outcome.

Disease specific QoL will be assessed using the St. George's Respiratory Questionnaire (SGRQ). The SGRQ has three subscale domains (Symptoms, Activity, and Impacts), which range from 0-100, where a higher value indicates a worse outcome. The total SGRQ is the average of these subscale domains and is on a scale of 0-100, where a higher value is a worse outcome.

Collection of PAP adherence data from the smart card of the PAP machine or from online data.

A visual analog scale to determine preference to CPAP vs NIPPV therapy. A scores will range from -10 to +10, where a higher score is better.

Fatigue Severity Scale (FSS): FSS measures how fatigue affects motivation, exercise, physical functioning, carrying out duties, interfering with work, family, or social life. Where a higher value is a worse outcome.

In a subgroup of patients, the investigators will perform Word-pair test and PVT before and after sleep period, this is an exploratory measure.

Test is being done to evaluate for presence or absence of hypercapnia