Untreated obstructive sleep apnea (OSA) is associated with excessive daytime sleepiness and, in population studies, with hypertension, stroke, diabetes, increased all-cause mortality, and substantial economic costs to the health care system.
Key Points
- Obstructive sleep apnea (OSA) is estimated to affect 9%–28% of women and 24%–26% of men in the US at a treatable level, based on a 2014 review; these figures are sensitive to hypopnea scoring criteria and study era (see below).
- Untreated OSA is associated with hypertension (Marin et al., 2012), and with increased risk of stroke and all-cause mortality (Marshall et al., 2014); the same cohort identified OSA as an independent risk factor for incident diabetes (Marshall et al., 2009).
- The economic burden of untreated OSA has been estimated at a magnitude comparable to diabetes, driven largely by lost productivity and motor vehicle collisions, based on a 2002 US analysis (Rakel, 2009; Sassani et al., 2004).
- Diagnosis requires a sleep study; treatment is not one-size-fits-all — CPAP, oral appliance therapy, and other options each fit different patients and severities.
- Effective treatment is only as good as the patient actually uses it — consistent nightly use matters as much as device type.
What Is Obstructive Sleep Apnea?
During sleep, the muscles of the throat relax. In OSA, the airway narrows or collapses repeatedly, cutting off or reducing airflow for seconds at a time. Each event can trigger a brief arousal — often too short to remember — that fragments sleep without the person ever fully waking up. Over a night, this can happen dozens or hundreds of times.
The physiological effects of OSA extend beyond daytime sleepiness. Repeated drops in oxygen saturation and repeated arousals are associated with ongoing cardiovascular and metabolic strain, which is reflected in the population-level health outcomes described below.
OSA is common: a 2014 review estimated prevalence at 9%–28% among women and 24%–26% among men in the US at a treatable level. These figures are sensitive to the hypopnea scoring criteria and study populations used at the time; more recent epidemiology applying updated American Academy of Sleep Medicine (AASM) scoring criteria has produced different prevalence estimates.
What Untreated OSA Actually Costs
Health costs. Untreated OSA is associated with excessive daytime sleepiness, impaired cognition, and mood changes in the short term. Over the longer term, population studies have linked it to hypertension (Marin et al., JAMA 2012), and to increased risk of stroke, cancer incidence, and all-cause mortality over 20 years of follow-up in the Busselton Health Study cohort (Marshall et al., J Clin Sleep Med 2014). The same cohort found sleep apnea to be an independent risk factor for incident diabetes (Marshall et al., J Clin Sleep Med 2009). OSA also carries a high rate of comorbidity with obesity, meaning many patients are managing several interacting conditions at once, not sleep apnea in isolation.
Economic and safety costs. The societal cost of untreated OSA has been estimated to approach the same magnitude as diabetes — including an estimated $132 billion in a 2002 US analysis, of which $15.9 billion was attributed to roughly 800,000 motor vehicle collisions linked to OSA-related impairment (Rakel, 2009; Sassani et al., Sleep 2004). Modeling estimates in this literature suggest that treatment could reduce collision-related costs, though this reflects economic modeling rather than a prospective interventional outcome trial.
These figures come from population-level health economic modeling, not a guarantee about any individual’s outcome. They describe risk at scale, not a prediction for one patient.
How Is It Diagnosed?
OSA is diagnosed with a sleep study — either an in-lab polysomnogram or, for many patients, a home sleep apnea test. The study measures the apnea-hypopnea index (AHI): the number of breathing pauses or significant reductions in airflow per hour of sleep. Severity is generally classified as mild, moderate, or severe based on the AHI together with symptoms such as daytime sleepiness, and is interpreted alongside oxygen desaturation and other findings from the study. AHI values can vary depending on which hypopnea scoring rule is applied by the sleep laboratory, which is one reason prevalence and severity figures differ across studies and eras (see above). A formal diagnosis is what allows a clinician to match treatment intensity to disease severity — it is also typically required for insurance coverage of therapy.
Which Treatment Is Right for Me?
There is no single correct therapy for every patient. The choice depends on OSA severity, airway anatomy, comorbidities, and — critically — which device a patient will actually wear night after night. Research distinguishes efficacy (how well a treatment performs when used correctly) from effectiveness (how well it performs in real-world use, where consistent nightly use is often the limiting factor).
| Option | What the evidence shows | Best suited to |
|---|---|---|
| CPAP (continuous positive airway pressure) | High efficacy at preventing airway collapse when used as prescribed; considered first-line therapy, but real-world effectiveness is often limited by compliance | Moderate to severe OSA; patients able to tolerate nightly mask use |
| Oral appliance therapy | Mechanically repositions the mandible to enlarge upper airway cross-sectional area and alter soft-tissue geometry; lower per-night efficacy than CPAP but often better nightly adherence, which narrows the real-world effectiveness gap | Mild to moderate OSA, or CPAP-intolerant patients |
| Upper airway/nerve stimulation | An emerging option that increases upper airway muscle tone during sleep | Select patients, typically after other options have failed |
| Nasal surgery (septoplasty, turbinate reduction) | Meta-analysis data show modest pre-to-post AHI change; generally considered adjunctive rather than definitive monotherapy for OSA | Patients with significant nasal obstruction, often alongside another primary therapy |
For oral appliance therapy specifically, efficacy should be confirmed with objective follow-up testing (for example, a repeat sleep study) after titration is complete, since subjective symptom improvement does not reliably predict AHI reduction. Recognized side effects include temporomandibular joint (TMJ) symptoms, occlusal or bite changes, and tooth discomfort; patients should be monitored for these during treatment.
The practical takeaway from the efficacy-versus-effectiveness research: a therapy a patient uses every night can outperform, in real-world terms, a therapy with higher theoretical efficacy that goes unused. That’s part of why treatment selection is individualized rather than protocol-driven.
When to See a Specialist
Snoring, witnessed breathing pauses, morning headaches, unrefreshing sleep, or daytime sleepiness that affects driving or concentration all warrant evaluation. Patients already diagnosed with OSA who cannot tolerate CPAP should be evaluated for oral appliance therapy or other alternatives rather than discontinuing care. The population studies cited above compared treated with untreated OSA broadly; they did not test oral appliance therapy specifically against no treatment on hypertension, stroke, or mortality endpoints, so outcome equivalence between OAT and CPAP for these endpoints has not been established by this evidence base.
For Referring Providers
The literature summarized here supports two clinical points relevant to referral decisions. First, the cited population studies associate downstream risk — hypertension, stroke, incident diabetes, and mortality — with untreated OSA broadly rather than with failure of a specific therapy; these studies did not test oral appliance therapy specifically against no treatment on these endpoints, and outcome equivalence between OAT and CPAP for hard cardiovascular and metabolic endpoints has not been established. What the evidence does support is that patients who fail or refuse CPAP warrant evaluation for an alternative rather than discontinuation of care. Second, the efficacy/effectiveness distinction matters clinically: nightly adherence narrows the gap between CPAP’s higher per-night efficacy and an oral appliance’s typically lower per-night efficacy, which is relevant when counseling patients on options after CPAP failure — though this pertains to AHI reduction on the device, not to confirmed equivalence in cardiovascular or mortality outcomes. Oral appliance therapy efficacy should be confirmed with objective follow-up testing after titration, and patients should be monitored for TMJ symptoms, occlusal changes, and tooth discomfort during treatment. Diagnostic confirmation (polysomnography or validated home testing) remains the basis for therapy selection and for oral appliance therapy coding and coverage.
References
- Marin JM, Agusti A, Villar I, et al. Association between treated and untreated obstructive sleep apnea and risk of hypertension. JAMA. 2012;307:2169–2176.
- Marshall NS, Wong KK, Cullen SR, Knuiman MW, Grunstein RR. Sleep apnea and 20-year follow-up for all-cause mortality, stroke, and cancer incidence and mortality in the Busselton Health Study cohort. J Clin Sleep Med. 2014;10:355–362.
- Marshall NS, Wong KK, Phillips CL, Liu PY, Knuiman MW, Grunstein RR. Is sleep apnea an independent risk factor for prevalent and incident diabetes in the Busselton Health Study? J Clin Sleep Med. 2009;5:15–20.
- Rakel RE. Clinical and societal consequences of obstructive sleep apnea and excessive daytime sleepiness. Postgrad Med. 2009;121:86–95.
- Sassani A, Findley LJ, Kryger M, Goldlust E, George C, Davidson TM. Reducing motor-vehicle collisions, costs, and fatalities by treating obstructive sleep apnea syndrome. Sleep. 2004;27:453–458.
