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

Bohn E, Tangri N, Gali B, Henderson B, Sood MM, Komenda P, Rigatto C - BMC Nephrol (2013)

Bottom Line: Clinical outcomes of dialysis patients are variable, and improved knowledge of prognosis would inform decisions regarding patient management.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).

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Manitoba, Winnipeg, Canada. crigatto@sbgh.mb.ca.

ABSTRACT

Background: Clinical 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.

Methods: Eight 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.

Results: The 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.

Conclusions: Neither 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.

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Related in: MedlinePlus

Clinical assessment of cardiothoracic ratio and aortic arch calcification. A) Measurement of cardiothoracic ratio (CTR). CTR is equal to the maximal cardiac width divided by thoracic width, as shown. B) Assessment of aortic calcification using chest x-ray (lateral lumbar and abdominal CT for comparison with calcification enclosed by white boxes), with examples of grade 0–3 shown. Permission pending for reproduction of this image [12].
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Figure 1: Clinical assessment of cardiothoracic ratio and aortic arch calcification. A) Measurement of cardiothoracic ratio (CTR). CTR is equal to the maximal cardiac width divided by thoracic width, as shown. B) Assessment of aortic calcification using chest x-ray (lateral lumbar and abdominal CT for comparison with calcification enclosed by white boxes), with examples of grade 0–3 shown. Permission pending for reproduction of this image [12].

Mentions: The grade of aortic arch calcification was assessed using a previously validated scoring system: grade 0 (no visible calcification), grade 1 (small spots of calcification or single thin calcification of the aortic knob), grade 2 (one or more areas of thick calcification), and grade 3 (circular calcification of the aortic knob) [20]. The cardiothoracic ratio was calculated as the ratio of maximum transverse cardiac diameter in millimeters to maximum thoracic diameter in millimeters. Both AAC grading and CTR measurement are illustrated in Figure 1. All measurements of AAC and CTR were assessed independently by two adjudicators, with disagreements resolved by a consensus measurement.


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

Bohn E, Tangri N, Gali B, Henderson B, Sood MM, Komenda P, Rigatto C - BMC Nephrol (2013)

Clinical assessment of cardiothoracic ratio and aortic arch calcification. A) Measurement of cardiothoracic ratio (CTR). CTR is equal to the maximal cardiac width divided by thoracic width, as shown. B) Assessment of aortic calcification using chest x-ray (lateral lumbar and abdominal CT for comparison with calcification enclosed by white boxes), with examples of grade 0–3 shown. Permission pending for reproduction of this image [12].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219436&req=5

Figure 1: Clinical assessment of cardiothoracic ratio and aortic arch calcification. A) Measurement of cardiothoracic ratio (CTR). CTR is equal to the maximal cardiac width divided by thoracic width, as shown. B) Assessment of aortic calcification using chest x-ray (lateral lumbar and abdominal CT for comparison with calcification enclosed by white boxes), with examples of grade 0–3 shown. Permission pending for reproduction of this image [12].
Mentions: The grade of aortic arch calcification was assessed using a previously validated scoring system: grade 0 (no visible calcification), grade 1 (small spots of calcification or single thin calcification of the aortic knob), grade 2 (one or more areas of thick calcification), and grade 3 (circular calcification of the aortic knob) [20]. The cardiothoracic ratio was calculated as the ratio of maximum transverse cardiac diameter in millimeters to maximum thoracic diameter in millimeters. Both AAC grading and CTR measurement are illustrated in Figure 1. All measurements of AAC and CTR were assessed independently by two adjudicators, with disagreements resolved by a consensus measurement.

Bottom Line: Clinical outcomes of dialysis patients are variable, and improved knowledge of prognosis would inform decisions regarding patient management.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).

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Manitoba, Winnipeg, Canada. crigatto@sbgh.mb.ca.

ABSTRACT

Background: Clinical 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.

Methods: Eight 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.

Results: The 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.

Conclusions: Neither 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.

Show MeSH
Related in: MedlinePlus