What happens if I don't wear my Continuous Positive Airway Pressure (CPAP) machine as prescribed?

What Happens If You Don't Wear Your CPAP Machine

If you don't wear your CPAP as prescribed, you face significantly increased risks of stroke, heart attack, and motor vehicle crashes, with untreated obstructive sleep apnea (OSA) increasing your cardiovascular death risk nearly 3-fold and stroke risk by 2-6 times depending on severity. 1

Immediate Return of Sleep Apnea Symptoms

• Your apnea-hypopnea index (AHI) returns to pre-treatment levels immediately when CPAP is not used, meaning your breathing stops repeatedly throughout the night 2
• Daytime sleepiness, fatigue, and cognitive impairment return within days of stopping CPAP 1
• Blood pressure control deteriorates, with increases of 1.4-7.2 mm Hg in systolic blood pressure when CPAP is discontinued 1

Cardiovascular and Stroke Risks

The most critical consequence is dramatically elevated cardiovascular risk, particularly for stroke and heart attack. 1

Primary Prevention (No Prior Cardiovascular Disease)

• Severe untreated OSA increases your risk of fatal or nonfatal cardiovascular events 3-fold (adjusted OR 2.87 for cardiovascular death; OR 3.17 for nonfatal events) 1
• Stroke risk increases progressively with OSA severity: moderate OSA (AHI 9.5-19.1) carries an adjusted OR of 1.86, while severe OSA (AHI >19.1) has an adjusted OR of 2.86 1
• Men face particularly high stroke risk, with an OR of 2.26 per 10 years with untreated sleep apnea 1

Secondary Prevention (After Stroke or Heart Disease)

• If you've already had a stroke, not using CPAP increases your recurrent stroke rate from 14% to 32% over 7 years 1
• The adjusted hazard ratio for nonfatal vascular events is 2.87 when CPAP is not used after stroke 1
• The number needed to treat is only 4.9 patients to prevent one new vascular event, meaning CPAP is highly effective when used 1

Women-Specific Risks

• Untreated OSA in women increases the composite outcome of stroke or coronary heart disease with an adjusted hazard ratio of 2.76 3
• The association is particularly strong for stroke in women (adjusted HR 6.44) compared to coronary heart disease 3

Motor Vehicle Crash Risk

Your crash risk increases by 243% (ranging from 21% to 489% higher) compared to drivers without OSA when CPAP is not used. 1

• Commercial truck drivers with untreated OSA have a 5-fold higher crash rate than matched controls 1
• CPAP treatment reduces crash risk to the same level as individuals without OSA (risk ratio 0.278) 1
• Among drivers who had crashes, 93% experienced their crash before CPAP treatment, with a 73% reduction in total crashes after starting CPAP 1

Loss of CPAP Benefits

When you stop using CPAP, you lose the protective effects that adherent users maintain:

• CPAP-treated patients have vascular event risks similar to healthy subjects and patients with mild untreated sleep apnea 1
• The adjusted hazard ratio for cardiovascular endpoints with CPAP treatment is 0.34, meaning a 66% risk reduction 1
• Quality of life improvements, reduced snoring, and improved mood all reverse when CPAP is discontinued 2

Critical Adherence Thresholds

The American Thoracic Society considers patients adherent if they use CPAP for more than 4 hours per night, though the goal is full-time use during all sleep. 1

• Even partial use (>2 hours/night with progress toward improved symptoms) is better than no use 1
• Medicare requires 4+ hours per night on 70% of nights within a 30-day period for continued coverage, though this threshold lacks strong evidence for optimal outcomes 1
• CPAP adherence patterns are typically established early in treatment, making early intervention for intolerance crucial 1

Common Pitfalls and Solutions

The most common reasons for non-compliance are nasal/pharyngeal problems and lack of perceived benefit. 4

• Patients with less severe OSA (lower oxygen desaturation index) are more likely to discontinue CPAP despite still facing cardiovascular risks 4
• Older patients have higher risk of nasal and pharyngeal side-effects severe enough to stop CPAP (OR 2.8 per 10 years) 4
• Heated humidification and mask adjustments can improve adherence and should be addressed immediately when problems arise 5
• Cognitive-behavioral interventions improve CPAP adherence and should be considered early 1

Important Nuance About Recent Evidence

One large randomized trial (SAVE trial) found no cardiovascular benefit from CPAP in patients with established cardiovascular disease, but this study had critical limitations: mean CPAP use was only 3.3 hours per night (below adherence threshold), and most participants had minimal daytime sleepiness 2. This contrasts sharply with the guideline-cited observational studies showing clear benefits with adequate CPAP use. The lack of benefit in this trial likely reflects inadequate adherence rather than true ineffectiveness of properly used CPAP. 2