Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico.
Instituto de Desarrollo e Innovación en Fisiología Respiratoria, Mexico City, Mexico.
BMJ Open Respir Res. 2024 Oct 14;11(1):e002341. doi: 10.1136/bmjresp-2024-002341.
This study aimed to evaluate pulmonary diffusing capacity for nitric oxide (DLNO) and pulmonary diffusing capacity for carbon monoxide (DLCO) in Mexican Hispanics born and raised at 2240 m altitude (midlanders) compared with those born and raised at sea level (lowlanders). It also aimed to assess the effectiveness of race-specific reference equations for pulmonary diffusing capacity (white people vs Mexican Hispanics) in minimising root mean square errors (RMSE) compared with race-neutral equations.
DLNO, DLCO, alveolar volume (VA) and gas transfer coefficients (KNO and KCO) were measured in 392 Mexican Hispanics (5 to 78 years) and compared with 1056 white subjects (5 to 95 years). Reference equations were developed using segmented linear regression (DLNO, DLCO and VA) and multiple linear regression (KNO and KCO) and validated with Least Absolute Shrinkage and Selection Operator. RMSE comparisons between race-specific and race-neutral models were conducted using repeated k-fold cross-validation and random forests.
Midlanders exhibited higher DLCO (mean difference: +4 mL/min/mm Hg), DLNO (mean difference: +7 mL/min/mm Hg) and VA (mean difference: +0.17 L) compared with lowlanders. The Bayesian information criterion favoured race-specific models and excluding race as a covariate increased RMSE by 61% (DLNO), 18% (DLCO) and 4% (KNO). RMSE values for VA and KCO were comparable between race-specific and race-neutral models. For DLCO and DLNO, race-neutral equations resulted in 3% to 6% false positive rates (FPRs) in Mexican Hispanics and 20% to 49% false negative rates (FNRs) in white subjects compared with race-specific equations.
Mexican Hispanics born and raised at 2240 m exhibit higher DLCO and DLNO compared with lowlanders. Including race as a covariate in reference equations lowers the RMSE for DLNO, DLCO and KNO and reduces FPR and FNR compared with race-neutral models. This study highlights the need for altitude-specific and race-specific reference equations to improve pulmonary function assessments across diverse populations.
本研究旨在评估在 2240 米海拔高度（中海拔者）出生和成长的墨西哥裔西班牙人与在海平面（低海拔者）出生和成长的人之间的肺一氧化氮弥散量（DLNO）和肺一氧化碳弥散量（DLCO）。它还旨在评估种族特异性参考方程（白人 vs 墨西哥裔西班牙人）与种族中性方程相比，在最小化均方根误差（RMSE）方面的有效性。
在 392 名墨西哥裔西班牙人（5 至 78 岁）中测量了 DLNO、DLCO、肺泡容积（VA）和气体转移系数（KNO 和 KCO），并与 1056 名白人受试者（5 至 95 岁）进行了比较。使用分段线性回归（DLNO、DLCO 和 VA）和多元线性回归（KNO 和 KCO）来制定参考方程，并使用最小绝对收缩和选择算子进行验证。使用重复 k 折交叉验证和随机森林进行种族特异性和种族中性模型之间的 RMSE 比较。
与低海拔者相比，中海拔者的 DLCO（平均差异：+4 mL/min/mm Hg）、DLNO（平均差异：+7 mL/min/mm Hg）和 VA（平均差异：+0.17 L）更高。贝叶斯信息准则支持种族特异性模型，排除种族作为协变量会使 RMSE 增加 61%（DLNO）、18%（DLCO）和 4%（KNO）。VA 和 KCO 的 RMSE 值在种族特异性和种族中性模型之间相当。对于 DLCO 和 DLNO，与种族特异性方程相比，种族中性方程在墨西哥裔西班牙人中导致 3%至 6%的假阳性率（FPR），在白人受试者中导致 20%至 49%的假阴性率（FNR）。
在 2240 米海拔高度出生和成长的墨西哥裔西班牙人表现出较高的 DLCO 和 DLNO，与低海拔者相比。在参考方程中包含种族作为协变量可以降低 DLNO、DLCO 和 KNO 的 RMSE，并降低与种族中性模型相比的 FPR 和 FNR。本研究强调需要特定海拔和特定种族的参考方程来改善不同人群的肺功能评估。
