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 Table of Contents  
Year : 2022  |  Volume : 10  |  Issue : 1  |  Page : 9-13

Risk factor profile, incidence, and relevance of Mehran risk score to predict contrast-induced nephropathy in patients undergoing percutaneous coronary intervention

1 Department of Cardiology, Nizam's Institute of Medical Sciences, Hyderabad, Telangana, India
2 Department of Pathology, Skims Medical College, Bemina, Srinagar, Jammu and Kashmir, India

Date of Submission01-Feb-2022
Date of Decision16-Feb-2022
Date of Acceptance07-Mar-2022
Date of Web Publication13-Apr-2022

Correspondence Address:
Dr. N Rama Kumari
Department of Cardiology, Nizam's Institute of Medical Sciences, Hyderabad - 500 082, Telangana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/heartindia.heartindia_9_22

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Background: Contrast-induced nephropathy (CIN) is a grave but underdiagnosed complication of percutaneous coronary intervention (PCI) that is associated with increased in-hospital morbidity and mortality. Our aim was to study the incidence, risk factors of CIN, and applicability of Mehran risk score (MRS) in Indian population.
Materials and Methods: A total number of 432 patients were enrolled in the study. Inclusion criteria were patients with acute coronary syndrome or chronic stable angina who underwent PCI. Baseline parameters of patients were noted and patients were followed for development of CIN.
Results: The mean age of the study population was 57.2 + 10.43 years; males were 348 (80.6%) and females 84 (19.4%). Hypertension was present in 257 patients (59.5%), diabetes in 208 (48.1%), smoking in 208 (48.1%), anemia in 104 (24.1%), and heart failure in 95 (22%); the mean estimated glomerular filtration rate (eGFR) was 88.4 + 30.65 ml/min/1.73 m2 and the mean contrast volume usage was 122.8 + 41.9 ml. 64 patients (14.8%) developed CIN. On univariate analysis, age (P = 0.435), gender (0.125), hypertension (0.679), diabetes (0.177), and contrast volume (0.155) were not associated with the development of CIN, whereas smoking (0.021), hypotension (<0.001), heart failure (<0.001), anemia (0.001), and median eGFR (P < 0.001) were significantly associated with the development of CIN. However, on multivariate regression analysis, smoking was not associated with the development of CIN (P = 0.104). The incidence of CIN was 2.7-fold higher (odds ratio [OR]: 2.68, 95% confidence interval [CI]: 1.299–5.540, P = 0.008) in the intermediate group (MRS 6-10), 5.4-fold higher (OR: 5.403, 95% CI: 2.249–12.978, P < 0.001) in the high-risk group (MRS 11–15), and 51-fold higher (OR: 51.059, 95% CI: 18.195–143.278,P < 0.001) in the very high-risk groups (MRS >16) when compared to the low-risk group (MRS < 5). Dialysis was required only in 2 (3.1%) patients (P < 0.022).
Conclusions: The overall incidence of CIN was 14.8%. The incidence of CIN in the very high-risk group (MRS >16) was substantially higher in our study (77.8%) as compared to the same group in Mehran study (57.3%).

Keywords: Contrast-induced nephropathy, Mehran risk score, percutaneous coronary intervention

How to cite this article:
Kakroo SA, Kumari N R, Lateef MA, Archana R. Risk factor profile, incidence, and relevance of Mehran risk score to predict contrast-induced nephropathy in patients undergoing percutaneous coronary intervention. Heart India 2022;10:9-13

How to cite this URL:
Kakroo SA, Kumari N R, Lateef MA, Archana R. Risk factor profile, incidence, and relevance of Mehran risk score to predict contrast-induced nephropathy in patients undergoing percutaneous coronary intervention. Heart India [serial online] 2022 [cited 2022 Sep 29];10:9-13. Available from: https://www.heartindia.net/text.asp?2022/10/1/9/343072

  Introduction Top

Coronary artery disease is one of the major causes of death across the world and causes increased morbidity, mortality, and health-care costs. To revascularize significant coronary artery disease, percutaneous coronary intervention (PCI) is offered in majority of the patients.[1] Contrast media used to visualize the coronary vascular lumen might result in acute kidney injury after the procedure, known as contrast-induced nephropathy (CIN). The development of CIN after PCI results in increased morbidity and mortality.[2],[3],[4],[5]

The exact cause leading to CIN remains unanswered. The proposed causes for the development of CIN include hypoxia due to imbalance between local vasodilators and vasoconstrictors, generation of reactive oxygen species, viscous contrast media flowing through long, narrow caliber vessels of renal medulla, and direct cytotoxic effect.[6] Contrast-induced nephropathy defined as an increase of serum creatinine of more than 0.5 mg/dl or 25% above baseline within 48 h of administration of contrast media.[7] It usually develops within first 24–48 h, peaks by 3–5 days, and returns to baseline by 7 days.[8]

Other predisposing factors for the development of CIN include dehydration, diabetes, anemia, elderly age group, presence of heart failure, and preexisting renal dysfunction. These predisposing factors along with other risk factors have been combined together to formulate a risk model for the prediction of CIN by Mehran et al., known as Mehran risk score (MRS). Higher the score, more chances of CIN. MRS was formulated on a cohort group from Western population. In our study, in addition to studying the risk factor profile, incidence of contrast nephropathy, we applied the MRS to predict CIN to determine its applicability in Indian population.

  Aims Top

  1. To determine CIN incidence in patients undergoing PCI
  2. To determine the predisposing factors for the development of CIN
  3. Relevance of MRS in predicting CIN in our study population.

  Materials and Methods Top

It was an observational study done between March 2019 and March 2020.

Recruitment and method

This study was done after explaining the study details in a language understandable to the patient. The patient was provided with information sheet and a proper informed consent was taken. Our study population included 432 patients.

Inclusion criteria

  1. Patients with a diagnosis of acute coronary syndrome or chronic stable angina who underwent PCI.

Acute coronary syndrome diagnosis was based on the fourth universal definition of myocardial infarction defined by standard criteria of elevation of cardiac troponin levels with presence of at least one of the followings: chest pain, ischemic changes in electrocardiogram, imaging evidence of new abnormality in the wall motion, or presence of thrombus in the coronary artery on coronary angiography.

Exclusion criteria

  1. Pregnancy
  2. Allergic to contrast media
  3. Chronic kidney disease on regular dialysis
  4. Cardiogenic shock
  5. Unwillingness to give consent.

Patients' details regarding age, gender, risk factors, and indication for intervention were noted. Only those patients who fulfilled the criteria for PCI according to established guidelines were included in the study. The volume of contrast used was determined by the interventionist.

Baseline investigations of all patients were sent before the procedure. Predictors of CIN which are included in the MRS model were noted down and risk stratification of the patients was done for prediction of CIN. MRS model includes the following variables: hypotension characterized by systolic blood pressure of <80 mmHg, requirement of intra-aortic balloon pump, presence of heart failure, age >75 years, presence of anemia, diabetes, volume of contrast media used, and creatinine clearance measured by estimated glomerular filtration rate (eGFR). Higher the risk score, higher the incidence of CIN with score <5 and score >16 having CIN risk of 7.5% and 57.3%, respectively.

Before the start of the procedure, serum creatinine levels were noted and estimated GFR was calculated according to the Modification of Diet in Renal disease formula. Following the procedure, serum creatinine levels were noted down at 24 and 48 h, respectively, and increase of more than 0.25 mg/dl or more than 25% above preprocedure levels was considered as CIN after excluding other causes of acute kidney injury.


The incidence of CIN was determined by the percentage of total number of patients who developed rise in serum creatinine consistent with CIN.

Statistical analysis

Details collected from the patients were fed in Excel sheet and analyzed using STATA 15. Continuous variables were denoted by mean and standard deviation, whereas categorical variables were denoted as percentage. The incidence of CIN was reported in percentage with associated 95% confidence interval (CI). Unadjusted odds ratio was determined individually for all risk factors. Relationship between two categorical variables was determined by Chi-square test. Independent effect of risk factors on the development of CIN was assessed by a multivariate binary logistic regression model. Adjusted odds ratio (OR) was reported as well. P value was determined and a value of <0.05 was considered statistically significant.

  Results Top

In our study, 432 patients who were enrolled for the study underwent PCI and were followed for the development of CIN. Out of these, 132 patients underwent PCI under optical coherence tomography guidance [Table 1].
Table 1: Baseline parameters and risk factors for contrast-induced nephropathy

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Patients were grouped according to MRS into low, intermediate, high-risk, and very high-risk groups [Table 2].
Table 2: Patient grouping according to Mehran risk score

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The patients were followed for the development of CIN. Majority of the patients (61.3%) belonged to the low-risk category (MRS <5). Only 6.3% of patients belonged to very high-risk category (MRS >16).

Among the 432 patients, only 64 patients (14.8%) developed CIN [Figure 1].
Figure 1: Incidence of contrast-induced nephropathy

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Analysis of different risk factors with the development of CIN is shown in [Table 3]a.

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Subsequently, confounding variables were adjusted and analysis of categorical variables with CIN development was determined by multivariate logistic regression analysis [Table 3]b.

When the categorical variables were adjusted for other covariables, it was found out that hypotension, heart failure, and anemia were significant predictors for CIN development; however, smoking was not associated with CIN (P = 0.104].

The median estimated GFR in our study population of 432 patients was 96 ml/min/1.73 m2 [Table 1]. Out of these, 64 patients who developed CIN, median estimated GFR was 58 ml/min/1.73 m2 and among the 368 patients who did not develop CIN had a median estimated GFR of 98 ml/min/1.73 m2 and the difference was found to be significant (P < 0.001).

Among 432 patients, who were enrolled in the study, the median contrast volume of 100 ml was used. Out of these who developed CIN, the median use of contrast volume was 120 ml, whereas in those who did not develop CIN, the median use of contrast volume was 100 ml; however, the observed difference was insignificant (P = 0.155).

CIN incidence among various subgroups based on MRS is shown in [Table 4].
Table 4: Incidence of contrast-induced nephropathy across various Mehran risk score subgroups

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Patients were categorized into four MRS subgroups on the basis of MRS as low (MRS <5), intermediate (MRS 6–10), high (MRS 11–15), and very high risk (MRS >16), and the incidence of CIN in each subgroup was 6.4%, 15.5%, 27%, and 77.8%, respectively. Higher the risk score, higher was the incidence of CIN, the observation being statistically significant (P < 0.001) [Table 4].

The incidence of CIN was 2.7-fold higher, 5.4-fold higher, and 51-fold higher in the intermediate, high, and very high-risk Mehran groups, respectively, in comparison to Mehran low-risk group [Table 5].
Table 5: Tabulated form of higher likelihood of contrast-induced nephropathy in higher Mehran risk groups in comparison to low-risk Mehran group (reference group) respectively

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Out of 64 patients who developed CIN, dialysis was required in only 2 (3.1%) patients with P = 0.022.

  Discussion Top

In our study of 432 patients, who were followed for the development of CIN, 64 (14.8%) patients developed CIN, whereas 368 (85.2%) patients did not develop CIN. Mehran et al. (2004)[3] in their study found an incidence of 13.1% of CIN in post-PCI patients.

It was noted that the risk of CIN was exponentially higher with increasing MRS.

Our study and Mehran study were compared for the CIN incidence across various MRS subgroups, and it was found that the CIN incidence across low-, intermediate-, and high-risk groups were comparable between Mehran and our study; however, the CIN incidence among very high-risk group patients was substantially higher than the Mehran study [Table 6].
Table 6: Comparison of contrast-induced nephropathy risk in our study versus contrast-induced nephropathy risk in Mehran study

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MRS was developed and devised in western cohort, but its applicability in the Indian population holds true as well. The CIN incidence in the very high-risk group (MRS >16) was substantially higher in our study (77.8%) as compared to the same group in Mehran study (57.3%). Our observation was further validated by Sanjai Pattu Valappil et al.,[9] who conducted a similar study in South Indian population and found that the risk score is applicable to Indian population as well; however, CIN risk in the higher Mehran groups is considerably higher in the Indian population than in the Western population. The CIN incidence in the very high-risk group was 83.3% in their study, which was comparable to our study (77.8%) but significantly higher than the Mehran study (57.3%).

Limitations of the study

  1. The study was conducted at a single center and not a multicenter study
  2. Newer biomarkers of acute kidney injury were not evaluated in the study
  3. Latest Mehran study protocol was not included in this study
  4. Very high-risk group had less sample size.

  Conclusions Top

In our study of 432 patients,

  1. CIN incidence was 14.8%
  2. Predictability of CIN risk by MRS is applicable to Indian population as well
  3. Very high-risk groups (MRS >16) have a considerably higher CIN incidence in Indian population in comparison to Western population, but the difference may be because of the less sample size in very high Mehran risk group (MRS >16)
  4. Periprocedural hypotension, anemia, congestive heart failure, and baseline eGFR were significant predictors of CIN
  5. Patients who developed CIN required renal replacement therapy.

Ethical approval

Ethical Committee approval has been obtained.

Authors' contributions

All authors are contributed for this manuscript.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Shusterman N, Strom BL, Murray TG, Morrison G, West SL, Maislin G. Risk factors and outcome of hospital-acquired acute renal failure. Clinical epidemiologic study. Am J Med 1987;83:65-71.  Back to cited text no. 1
Hou SH, Bushinsky DA, Wish JB, Cohen JJ, Harrington JT. Hospital-acquired renal insufficiency: A prospective study. Am J Med 1983;74:243-8.  Back to cited text no. 2
Mehran R, Nikolsky E. Contrast-induced nephropathy: Definition, 30 epidemiology, and patients at risk. Kidney Int Suppl 2006;100:S11-5.  Back to cited text no. 3
McCullough PA, Wolyn R, Rocher LL, Levin RN, O'Neill WW. Acute renal failure after coronary intervention: Incidence, risk factors, and relationship to mortality. Am J Med 1997;103:368-75.  Back to cited text no. 4
Katzberg RW, Newhouse JH. Intravenous contrast medium-induced nephrotoxicity: Is the medical risk really as great as we have come to believe? Radiology 2010;256:21-8.  Back to cited text no. 5
Persson PB, Hansell P, Liss P. Pathophysiology of contrast medium-induced nephropathy. Kidney Int 2005;68:14-22.  Back to cited text no. 6
Gleeson TG, Bulugahapitiya S. Contrast-induced nephropathy. AJR Am J Roentgenol 2004;183:1673-89.  Back to cited text no. 7
Ribichini F, Graziani M, Gambaro G, Pasoli P, Pighi M, Pesarini G, et al. Early creatinine shifts predict contrast-induced nephropathy and persistent renal damage after angiography. Am J Med 2010;123:755-63.  Back to cited text no. 8
Valappil SP, Kunjukrishnapillai S, Iypea M, Koshy AG, Viswanathan S, Gupta PN, et al. Predictors of contrast induced nephropathy and the applicability of the Mehran risk score in high risk patients undergoing coronary angioplasty – A study from a tertiary care center in South India. Indian Heart J 2018;70:399-404.  Back to cited text no. 9


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]


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