Obstructive Sleep Apnoea: Snoring Isn't Trivial — STOP-BANG Self-Screening, How Sleep Testing Works, What CPAP Improves, and Why Kidney Patients Are So Often Affected

What obstructive sleep apnoea (OSA) is

During sleep the upper airway repeatedly collapses, causing pauses in breathing (apnoeas) or shallow breathing (hypopnoeas). Oxygen falls and the brain briefly wakes to restore breathing — dozens to hundreds of times a night, usually without the person remembering. The result is fragmented sleep and intermittent hypoxia, daytime sleepiness, and long-term cardiovascular and metabolic harm [1][2].

A 2019 Lancet Respiratory Medicine analysis estimated about 936 million adults aged 30–69 have OSA (AHI ≥5) and 425 million have moderate–severe disease (AHI ≥15); 80–90% are undiagnosed [3].

Symptoms: more than snoring

• Loud snoring, witnessed pauses in breathing or waking gasping
• Daytime sleepiness (dozing while driving or in meetings), fatigue, poor concentration
• Morning headache, dry mouth
• Nocturia ≥2 times a night (increased atrial natriuretic peptide)
• Hard-to-control hypertension (high despite 3 drugs)
• Low mood, irritability; sexual dysfunction

Women and older adults often present atypically (insomnia, fatigue, mood symptoms) and are easily missed [1].

Self-screening: STOP-BANG

Eight yes/no questions, one point each [4]:

0–2 low risk; 3–4 intermediate; 5–8 high. A score ≥3 is about 90% sensitive for moderate–severe OSA but not very specific, so it tells you whether to get tested, not whether you have it [4].

How sleep testing works

Diagnosis requires a sleep study; the key number is the AHI (apnoea–hypopnoea index), events per hour [1]:

• Polysomnography (PSG): an overnight stay in a sleep laboratory; the gold standard.
• Home sleep apnoea testing (HSAT): AASM 2017 supports home testing for adults with a high pre-test probability of moderate–severe OSA and no significant cardiopulmonary disease; a negative home test with strong clinical suspicion should be followed by PSG [1].
• Smartwatch "blood oxygen/sleep breathing" features cannot diagnose OSA, but abnormal readings are a reasonable prompt to seek assessment.

Treatment: CPAP is first-line, but not the only option

CPAP (continuous positive airway pressure)

A mask worn during sleep splints the airway open with air pressure. AASM 2019 strongly recommends it for OSA with sleepiness, and also to improve quality of life and blood pressure [2]:

• Daytime sleepiness: clear improvement (Epworth score falls 2–3 points on average).
• Blood pressure: average 2–3 mmHg reduction; larger (5–7 mmHg) in resistant hypertension [2].
• Cardiovascular events: the SAVE trial (2,717 patients) found CPAP did not reduce events, but average use was only 3.3 h/night [5]; observational data suggest greater benefit with ≥4 h/night. Current view: CPAP definitely improves symptoms and BP; its effect on hard cardiovascular outcomes depends on hours of use.
• Atrial fibrillation: treating OSA lowers recurrence after ablation.

Adherence is everything: aim for ≥4 h/night on ≥70% of nights. Poor mask fit, nasal congestion, dry mouth and claustrophobia all have fixes (different masks, humidifier, nasal spray) — don't quietly give up.

Alternatives

• Weight loss: 10% loss reduces AHI by about 26%; the GLP-1/GIP agonist tirzepatide reduced AHI by about 25–29 events/hour in SURMOUNT-OSA and in 2024 became the first US-approved drug for OSA (in obesity) [6].
• Mandibular advancement devices: for mild–moderate OSA or CPAP intolerance; slightly less effective than CPAP but better adherence [2].
• Side sleeping: works for positional OSA.
• Avoid alcohol and sedative-hypnotics (they relax pharyngeal muscles and worsen obstruction).
• Surgery and hypoglossal nerve stimulation: selected patients.

Why kidney patients are so often affected

OSA prevalence in dialysis patients is 50–60%, and about twice the general population in non-dialysis CKD [7]. Reasons:

• Fluid overload: fluid pooled in the legs by day shifts to the neck when lying down and narrows the pharynx (rostral fluid shift) — which is why more intensive ultrafiltration or nocturnal dialysis can improve OSA.
• Uraemia affects respiratory drive and upper-airway muscle tone.
• Co-morbidities: obesity, diabetes, heart failure.

Conversely, the intermittent hypoxia and sympathetic activation of OSA accelerate CKD progression and worsen hypertension and albuminuria [7]. Therefore:

• Kidney patients with snoring, nocturia, resistant hypertension or daytime sleepiness should raise sleep testing with their nephrologist.
• In dialysis, OSA symptoms are easily dismissed as "dialysis fatigue".
• Weight gain and steroids after transplant can trigger or worsen OSA.
• Sleeping pills (benzodiazepines, zolpidem) clear more slowly in CKD and worsen OSA — avoid.

When to seek care

Urgently: waking gasping with chest pain; severe morning headache with confusion; falling asleep while driving (stop driving until assessed).

Routine appointment: STOP-BANG ≥3; witnessed apnoeas; BP uncontrolled on 3 drugs; new atrial fibrillation; dialysis patient troubled by sleepiness or nocturia.

Questions to ask your doctor

1. What is my STOP-BANG score? Is home testing or a laboratory study more appropriate?
2. What are my AHI and lowest oxygen saturation?
3. Can my CPAP pressure or mask be adjusted? What does my usage data show?
4. (Dialysis) Would more ultrafiltration or a different schedule improve my sleep?
5. Could any of my sleeping pills or painkillers be worsening the apnoea?

References

1. Kapur VK, et al. AASM Clinical Practice Guideline for Diagnostic Testing for Adult OSA. J Clin Sleep Med. 2017;13(3):479–504. https://doi.org/10.5664/jcsm.6506
2. Patil SP, et al. Treatment of Adult OSA with Positive Airway Pressure: AASM Clinical Practice Guideline. J Clin Sleep Med. 2019;15(2):335–343. https://doi.org/10.5664/jcsm.7640
3. Benjafield AV, et al. Global prevalence and burden of OSA. Lancet Respir Med. 2019;7(8):687–698. https://doi.org/10.1016/S2213-2600(19)30198-5
4. Chung F, et al. STOP-Bang Questionnaire. Chest. 2016;149(3):631–638. https://doi.org/10.1378/chest.15-0903
5. McEvoy RD, et al. SAVE trial. N Engl J Med. 2016;375(10):919–931. https://doi.org/10.1056/NEJMoa1606599
6. Malhotra A, et al. SURMOUNT-OSA. N Engl J Med. 2024;391(13):1193–1205. https://doi.org/10.1056/NEJMoa2404881
7. Lin CH, Lurie RC, Lyons OD. Sleep Apnea and Chronic Kidney Disease: A State-of-the-Art Review. Chest. 2020;157(3):673–685. https://doi.org/10.1016/j.chest.2019.09.004

This article compiles publicly available medical information for educational purposes only. It is not medical advice and has not been reviewed by a practising physician. For any health or medication question, consult a qualified professional. For chest pain, sudden breathlessness, one-sided weakness or slurred speech, call your local emergency number or go to the emergency department immediately.