Table 2.
Study demographics and mathematical equations for studies from non-Asian countries. Definitions: %IBW = percent of ideal body weight, AHI = apnea-hypopnea index, BMI = body mass index (in kg/m2), CPAP = continuous positive airway pressure, cwp = centimeters of water pressure, ESS = Epworth Sleepiness Scale [71], HI = health index, Msat = mean saturation, nadir SaO2 = lowest oxygen saturation, NC = neck circumference, NR = not reported, Nsat = nadir saturation, ODI = oxygen desaturation index, PAP = positive airway pressure, Peff = effective pressure, Ppred = predicted pressure, pts = patients; RDI = respiratory disturbance index, spO2 = oxygen saturation, SSS = snoring severity score, USA = United States of America, and C, X, Y, and Z = coefficients based on artificial neural networks.
| Study group, year, and country | Number of pts Development (D) Validation (V) |
Mean age | Mean BMI | Mean AHI | Mathematical equation | Accuracy of formula |
|---|---|---|---|---|---|---|
| Basoglu and Tasbakan (2012), Turkey [15] | D = 250 V = 130 |
52.3 ± 10.3 | 32.3 ± 5.3 | 56.7 ± 22.8 | 0.148 × NC + (0.038 × ODI) | Within ±3 cwp in 96.2% of pts |
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| Tofts et al. (2012), USA [58] | D/V = 310 | NR | NR | NR | 5.55 + 0.05327 (HI) + 0.03276 (NC) + 0.03422 (AHI Crude) + 0.0005568 (AHI Supine) + 0.001110 (AHI REM) + 0.01301 (RDI) |
Predicts 30% of the variability while being within ±2 cwp 74% of the time |
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| Schiza et al. (2011), Greece [44] | D/V = 1111 | 54.6 ± 10.67 | 34.35 ± 6.03 | 41.5 ± 20.16 | Men: 5.16 + (0.003 × smoking in pack years) + (0.054 × BMI) + (0.016 × AHI) − 0.403 Women: 5.16 + (0.003 × smoking in pack years) + (0.054 × BMI) + (0.016 × AHI) − 0.806 |
Within ±2 cwp of the effective pressure in 95% of pts |
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| Anees (2010), USA [63] | V = 27 | — | — | — | 0.086 × BMI + 0.029 × SSS + 5.989 | Within ±2 cwp of CPAP titration in 44%; 2 cwp higher than predicted in 37% |
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| El Solh et al. (2007), USA [59] | D = 311 V = 98 |
49.6 ± 12.4 | 35 (34–37) | 33 (28–38) | X − NC + Y − BMI + Z × AHI + C | Correlation coefficients between the titration study and predicted pressure was 0.86. The equation underestimated optimal pressures |
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| Loredo et al. (2007), USA [34] | D/V = 76 | 47.6 ± 9.8 | 31.3 ± 5.4 | 55.5 ± 31.3 RDI | 30.8 + 0.03 × RDI − 0.05 × NSAT − 0.2 × MSAT | Equation predicted 67% of the variance for Peff |
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| Skomro et al. (2007), Canada [47] | D/V = 183 | 51 ± 11 | 37 ± 8 | 46 ± 33 | 6.2 × [BMI × 0.11] | Empiric CPAP pressure was suboptimal in 40% pts |
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| Torre-Bouscoulet et al. (2007/2009), Mexico [50, 51] | D/V = 100 | 49 ± 11 | 34 ± 4 | ≥30 | Men: (BMI × 0.09) + (ODI × 0.01) − (mean SpO2 × 0.06) + 11.9 Women: (BMI × 0.07) + (ESS × 0.1) + (ODI × 0.02) + 5.33 |
Poor agreement between 95% APAP pressures and predictive equations. Equations were not successful |
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| Panagou et al. (2005), Greece [64] | D = 26 | 51 ± 11.2 | — | — | 4.95 + (0.18 × AHI) − (0.133 × DI) | No validation testing |
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| Stradling et al. (2004), Britain [48, 49] | D = 101 V = 30 |
49.0 ± 10.5 | 36.5 ± 6.5 | (0.048 × 4% saO2 dips/h) + (0.128 × NC) + 2.1 | Considerable PAP variations from night to night. Similar results for APAP trial and CPAP titration | |
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| Rowley et al. (2005), USA [43] | D = 224 V = 192 |
50.5 ± 9.5 | 40.6 ± 8.8 | 32.0 ± 26.4 | (0.16 × BMI) + (0.13 × NC) + (0.04 × AHI) − 5.12 | Equation improves success rate of in lab titrations but equations were not as helpful for prescribing CPAP |
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| Sériès (2000), Canada [45] | D/V = 40 | — | — | 46.1 ± 26.3 | 0.193 × BMI + 0.077 × NC + 0.02 × AHI − 0.611 | Home APAP titration successfully predict fixed CPAP in 95% of pts |
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| Nahmias et al. (1995) [65] | D/V = 40 | — | — | 37.7 ± 3.3 | 8.7 + 0.028 × %IBW + 0.015 × RDI − 0.071 × nadir SaO2 |
In 73% of patients, the equation predicted CPAP ≥ CPAP titration study |
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| Teschler et al. (1995), Germany [60] | D = 77 V = 180 |
55 ± 10 | 30.9 ± 5.8 | 38 ± 21 | 1.95 + 0.80 × sex factor (men = 2, women = 1) + 0.09 × BMI + 0.01 × NC + 0.03 × AHI |
Mean CPAP pressure was 9.1 ± 2.0 cwp and the predicted was 8.4 ± 3.6 cwp. In 51% of pts the difference was greater than ±1 cwp |
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| Hoheisel and Teschler (1994), Germany [61] | — | — | — | — | (0.07 × NC) + (0.02 × BMI) + (0.03 × AHI) + 3.2 | Calculations were made to attempt to improve home prescriptions |
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| Miljeteig and Hoffstein (1993), Canada [38] | D = 208 V = 129 |
50 ± 11 | 34 ± 8 | 50 ± 31 | −5.12 + 0.13 × BMI + 0.16 × NC + 0.04 × AHI | Within ±2 cwp in 75% of pts. The equation accounted for 76% of the variability in CPAP |