Predicting risk of mortality in dialysis patients: a retrospective cohort study evaluating the prognostic value of a simple chest X-ray

Abstract

BackgroundClinical outcomes of dialysis patients are variable, and improved knowledge of prognosis would inform decisions regarding patient management. We assessed the value of simple, chest X-ray derived measures of cardiac size (cardiothoracic ratio (CTR)) and vascular calcification (Aortic Arch Calcification (AAC)), in predicting death and improving multivariable prognostic models in a prevalent cohort of hemodialysis patients.MethodsEight hundred and twenty-four dialysis patients with one or more postero-anterior (PA) chest X-ray were included in the study. Using a validated calcification score, the AAC was graded from 0 to 3. Cox proportional hazards models were used to assess the association between AAC score, CTR, and mortality. AAC was treated as a categorical variable with 4 levels (0,1,2, or 3). Age, race, diabetes, and heart failure were adjusted for in the multivariable analysis. The criterion for statistical significance was p<0.05.ResultsThe median CTR of the sample was 0.53 [IQR=0.48,0.58] with calcification scores as follows: 0 (54%), 1 (24%), 2 (17%), and 3 (5%). Of 824 patients, 152 (18%) died during follow-up. Age, sex, race, duration of dialysis, diabetes, heart failure, ischemic heart disease and baseline serum creatinine and phosphate were included in a base Cox model. Both CTR (HR 1.78[1.40,2.27] per 0.1 unit change), area under the curve (AUC)=0.60[0.55,0.65], and AAC (AAC 3 vs 0 HR 4.35[2.38,7.66], AAC 2 vs 0 HR 2.22[1.41,3.49], AAC 1 vs 0 HR 2.43[1.64,3.61]), AUC=0.63[0.58,0.68]) were associated with death in univariate Cox analysis. CTR remained significant after adjustment for base model variables (adjusted HR 1.46[1.11,1.92]), but did not increase the AUC of the base model (0.71[0.66,0.76] vs. 0.71[0.66,0.76]) and did not improve net reclassification performance (NRI=0). AAC also remained significant on multivariable analysis, but did not improve net reclassification (NRI=0). All ranges were based on 95% confidence intervals.ConclusionsNeither CTR nor AAC assessed on chest x-ray improved prediction of mortality in this prevalent cohort of dialysis patients. Our data do not support the clinical utility of X-ray measures of cardiac size and vascular calcification for the purpose of mortality prediction in prevalent hemodialysis patients. More advanced imaging techniques may be needed to improve prognostication in this population.

Association between the Hemoglobin Level and Cardiothoracic Ratio in Patients on Incident Dialysis

“…On the other hand, about 75% of our patients had a CTR >50%, which was higher than the 42% [17], 59% [31] and 67% [30] previously described, although the prevalence of cardiovascular disease was about 20% in the present and previous studies. We used a database that was created from information obtained when patients with ESKD started renal replacement therapy.…”

“…The mean and median CTRs in the present study were about 55%, which is similar to that found in a previous study of patients on HD [30]. On the other hand, about 75% of our patients had a CTR >50%, which was higher than the 42% [17], 59% [31] and 67% [30] previously described, although the prevalence of cardiovascular disease was about 20% in the present and previous studies.…”

Cardiac, Inflammatory and Metabolic Parameters: Hemodialysis versus Peritoneal Dialysis

“…The grade of AAC using a previously validated scoring system was assessed: grade 0 (no visible calcification), grade 1 (small spots of calcification or single thin calcification of the aortic handle), grade 2 (one or more areas of thick calcification) and grade 3 (circular calcification of the aortic knob). All measurements of AAC and CTR were assessed independently by three adjudicators, with disagreements resolved by a consensus measurement [31,32]. …”

“…It usually indicates the LV size and may provide reasonable estimates of vascular calcification [32]. …”

Prognostic Risk Stratification of Cardiac Events Evaluated by Aortic Calcification in Elderly Patients with Chronic Kidney Disease

“…The principal design of the J-ACCESS 3 study was previously described (5,6 showing aortic calcification in CXR. The aortic calcification was visually assessed using CXR (11). Eighty-two subjects were excluded as a CXR and echocardiography examination was not performed.…”