Association of Coexisting Hypertension and Diabetes with Blood Gas Analysis Indicators in COPD Patients: A Propensity...

Background: Hypertension and diabetes commonly coexist in patients with chronic obstructive pulmonary disease (COPD), but their associations with arterial blood gas parameters remain insufficiently characterized, particularly after accounting for measured differences in baseline characteristics. This study aimed to examine the associations between coexisting hypertension and diabetes and selected arterial blood gas parameters in older patients with COPD. Propensity score matching (PSM) was used to improve the comparability of the study groups and reduce confounding from measured baseline covariates. Patients and Methods: A retrospective cross-sectional study was conducted involving 1030 patients. The comorbidity group comprised COPD patients with both hypertension and diabetes (n = 340), while the COPD-only group refers to COPD patients without hypertension or diabetes (n = 690). Propensity score matching (PSM) was estimated using a regression model with covariates including age, sex, marital status, BMI, temperature, and pulse. Balance was assessed using standardized mean difference (SMD), and linear regression models were adopted to evaluate the association between coexisting hypertension and diabetes and each blood gas indicator (PCO₂, PO₂, SaO₂). Results: We performed 1:1 nearest-neighbor matching and successfully generated 340 matched pairs, forming a total matched cohort of 680 patients; all unmatched participants from the original 1030 subjects were excluded from subsequent outcome comparisons. Covariate balance was optimized for most baseline indicators after PSM, although mild residual imbalance remained in age and BMI after matching. The comorbidity group demonstrated a statistically significant reduction in PCO₂ (B: -2.54, 95% CI: -4.52 to -0.56) compared to the COPD-only group, while no significant differences were observed in PO₂ (B: -2.48, 95% CI: -7.6 to 2.64) or SaO₂ (B: -1.16, 95% CI: -2.67 to 0.35). In addition, a sensitivity analysis adjusting for age and BMI was conducted to evaluate the robustness of the findings. Conclusions: After propensity score matching, coexisting hypertension and diabetes were associated with lower PCO₂ levels in elderly COPD patients, while no significant associations were found for PO₂ or SaO₂.