BMI Limitations for Home Sleep Testing
There is no specific BMI limit that precludes the use of home sleep testing (HST), but caution should be exercised in patients with higher BMIs, particularly those with obesity-hypoventilation syndrome or other comorbidities. 1
Patient Selection Considerations
Home sleep testing has been successfully used in patients with varying BMI ranges, including those with mean BMIs of:
- 34 ± 7 kg/m²
- 34.6 ± 6.5 kg/m²
- 31.0 ± 6.6 kg/m² 1
The American College of Physicians clinical practice guidelines support the use of home sleep testing across a range of BMI values, with studies showing successful implementation in patients with BMIs in the obese range 2, 1.
When to Consider In-Lab Polysomnography Instead
While there is no absolute BMI cutoff, in-lab polysomnography may be more appropriate for patients with:
- Suspected obesity-hypoventilation syndrome
- Significant pulmonary disorders
- Unstable heart disease
- Other sleep disorders besides OSA 1
Diagnostic Accuracy Considerations
Several important factors should be considered when deciding between home sleep testing and in-lab polysomnography:
- Home sleep testing provides comparable diagnostic accuracy to in-lab polysomnography for moderate to severe OSA 1
- Home testing may be less reliable for diagnosing mild OSA 1
- In patients with higher BMIs, particularly those with severe obesity, the risk of undiagnosed central events or hypoventilation increases, which may not be adequately captured by some home sleep testing devices 3
Body Position Effects
An important consideration is that body position during sleep can affect OSA severity differently between home and lab settings:
- In-lab polysomnography may artificially increase OSA severity in some patients by inducing changes in body position compared to the home environment 4
- This effect may be more pronounced in patients with more severe OSA 4
Practical Approach
When considering home sleep testing for patients with elevated BMI:
For patients with uncomplicated obesity (even with BMI >30) without significant comorbidities and high pre-test probability of moderate-to-severe OSA, home sleep testing is appropriate 1, 5
For patients with morbid obesity (typically BMI >40) or obesity with comorbidities (heart failure, pulmonary disease, neuromuscular disorders), consider in-lab polysomnography as the initial test 1, 6
If home sleep testing is negative in a patient with high clinical suspicion for OSA, proceed to in-lab polysomnography for definitive evaluation 5
The quality of sleep tends to be better at home, with studies showing greater sleep duration and efficiency in the home setting compared to the laboratory 7, which may provide a more accurate representation of the patient's typical sleep patterns.