Data sources and study population
This is an observational cohort, single-center, retrospective study. The data we used in this study was based on the electronic clinical management records system of the Guangdong Provincial People’s Hospital (ClinicalTrials.gov NCT04407936). We collected data on all-cause mortality through the Guangdong Provincial Public Security and then matched to the electronic clinical management system of the Guangdong Provincial People’s Hospital records. The baseline data included demographic characteristics, medical history, laboratory test results and medication use. We included patients undergoing coronary angiography (CAG) and with a final diagnosis of CAD complicated by CHF in accordance with the 10th Revision Codes of the International Classification of Diseases (ICD-10; I20.xx–I25.xx, I50.00001, and I91.40001, Supplemental Table S1) from January 2007 to December 2018. Percutaneous coronary intervention (PCI) or coronary angiography (CAG) was performed in accordance with authoritative clinical practice guidelines[18, 19]. All blood samples were collected in the early morning after overnight fasting. We excluded patients who lacked platelet counts, hemoglobin levels, and follow-up information. Finally, 2,599 were enrolled in this analysis (Figure 1). The study population was dichotomized based on the PHR on admission according to the median, and we define PHR˂1.69 as low PHR (group 1), PHR≥1.69 as high PHR (group 2).
Clinical definition
CHF was defined as New York Heart Association (NYHA) class>2 or Killip class>1[20]. Acute myocardial infarction (AMI) was defined as having a medical history of an ST-elevated myocardial infarction (STEMI) or Non-STEMI cardiac events. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m2. eGFR was calculated according to the Modification of Diet in Renal Disease (MDRD) equation. Hypertension (HT) and diabetes mellitus (DM) were defined following the 10th Revision Codes of the International Classification of Diseases.
Study endpoints and clinical follow-up
Long-term all-cause mortality was the primary endpoint of this study which was defined as any death recorded from the date of enrollment to the date of the last follow-up visit. Follow-up time and data on long-term all-cause mortality were obtained from the Guangdong Provincial Public Security and then matched to the electronic Clinical Management System of the Guangdong Provincial People’s Hospital records.
Statistical Analysis
Descriptive statistics on baseline variables are presented as the mean (standard deviation [SD]), median (interquartile range [IQR]), or number and percentage as appropriate. Differences in baseline characteristics between groups were analyzed by Student’s t-test when appropriate. The categorical data was analyzed by Pearson chi-squared tests. Restricted cubic splines were used to investigate the associations of PHR and long-term all-cause death. Survival times were plotted using Kaplan-Meier survival curves, the log-rank test was used to compare differences in survival.
The usefulness of PHR for independently predicting long-term all-cause mortality among CAD patients with CHF was analyzed by the Cox regression models. Hazard ratios (HRs) and 95% confidence intervals (CIs) are reported. Those related to mortality on the basis of clinical experience were further controlled using multivariable Cox regression in 3 different models. Model 1 was unadjusted, model 2 adjusts for age and gender, and model 3 included model 2 variables, medical history (CKD, HT, AMI, Stroke, DM, pre-acute myocardial infarction, PCI and anemia), drugs information (angiotensin-converting enzyme inhibitor/angiotensin receptor blockers, aspirin, β-blockers, clopidogrel and statins). Subgroup analysis was performed among 8 prespecified subgroups (age≥75 or age<75, male or female, non-CKD or CKD, non-PCI or PCI) to assess the association of PHR with long-term all-cause mortality among CAD patients with CHF.
All P values were calculated with two-sided tests, a threshold of p-value<0.05 was set to represent statistical significance. All data analyses were performed by R software (version 4.0.3; R Core Team, Vienna, Austria).