Gillesén M, Fedchenko M, Giang KW, Dimopoulos K, Eriksson P, Dellborg M, Mandalenakis Z. Eur Heart J Open. 2022 Sep 2;2(5):oeac055. doi: 10.1093/ehjopen/oeac055. eCollection 2022 Sep.PMID: 36213331 Free PMC article.
Commentary by Dr. Helen Parry (Leeds, UK), section editor of ACHD Journal Watch:
Introduction:
Whilst acute kidney injury is a common complication following cardiac surgery for congenital heart disease, it is unclear whether these patients go on to develop chronic kidney disease (CKD). Studies show there are relatively high rates of CKD in patients with congenital heart disease.
Methods:
Data were taken from the Swedish National Patient Register and the cause of death register, patients with congenital heart disease born between 1970 and 2017 were identified. Each case was matched to 10 controls for age and sex taken from the Swedish population register. Chronic kidney disease, acute kidney injury and hypertension were defined by presence of the relevant ICD codes on the register.
Patients with congenital heart disease were analyzed as a group and categorized into 6 groups:
- Cono-truncal defects including common arterial trunk, aortopulmonary septum defect and transposition of the great arteries.
- Severe, non-cono-truncal defects including endocardial cushion defect, common ventricle and hypoplastic left heart syndrome.
- Coarctation of the aorta
- Ventricular septal defects
- Atrial septal defects
- All other heart and circulatory anomalies
In the presence of multiple diagnoses, the classification was based on the most severe pathology.
Analysis was performed using the Chi squared test for categorical variables and the Student’s t test for nominal variables. Increased rate of CKD was reported per 100000 person years. Death from all causes was accounted for as a competing risk. Cox regression models were used to generate hazard ratios with confidence intervals accounting for acute kidney injury, hypertension, and diabetes. Patients were divided into age categories for regression modelling: 0-17 years, 18-39 years and >40 years.
Results
A total of 71 936 patients with congenital heart disease were identified:
- 50.2% were male
- Mean birth year 1999
- Most common lesions VSD (31.9%) and all other heart and circulatory abnormalities (30.2%)
During a median follow up of 13.5 years for patients and 15.5 years for controls, almost 0.5% of patients with congenital heart disease developed CKD compared to 0.1% controls.
Hazard ratios for CKD in patients with congenital heart disease are provided below in the table adapted from the text:
| Lesion Group | Number (%) patients with congenital heart disease and CKD | Hazard ratio for CKD (95% CI) | Adjusted hazard ratio for CKD accounting for hypertension, AKI and diabetes mellitus (95% CI) |
| All Congenital heart disease | 379 (0.5) | 6.41 (5.65-7.27) | 4.37 (3.83-5.00) |
| Conotruncal defects | 39 (0.7) | 7.62 (5.17-11.24) | 6.62 (4.43-9.89) |
| Severe non-conotruncal defects | 34 (0.8) | 11.31 (7.37-17.36) | 6.79 (4.24-10.82) |
| Coarctation | 25 (0.7) | 9.66 (5.68-16.42) | 6.74 (3.62-12.55) |
| VSDs | 81 (0.4) | 5.39 (4.13-7.05) | 4.31 (3.25-5.72) |
| ASDs | 64 (0.4) | 7.40 (5.36-10.21) | 6.57 (4.67-9.26) |
| Other heart and circulatory abnormalities | 136 (0.6) | 5.58 (4.55-6.86) | 3.59 (2.88-4.49) |
The most prevalent risk factor before a CKD diagnosis was hypertension (21.1%, n=80), followed by previous acute kidney injury (15.0%, n=57) then diabetes mellitus (4.2%, n=16).
Discussion and clinical implications:
The take home message was that patients with congenital heart disease have a 6-fold increase in risk of developing CKD. However, the incidence of CKD in congenital heart disease appears to be lower than in previous cohort studies. The patients with the greatest likelihood of developing CKD were those with conotruncal abnormalities or severe defects that were not conotruncal abnormalities. This is thought to relate to chronic hypoperfusion, maladaptive repair and fibrogenesis.
The risk of chronic kidney disease was higher in patients born 1997-2017 compared to 1970-1996. It was though this could be partly explained by survival bias.
The authors point out some of the limitations of their study including the uncertainty relating to ICD codes. They suggest the clinical impact of the study will be to prompt further work looking at potential interventions to prevent development on CKD in this group.
Positive points:
- Relatively large sample size for a study in congenital heart disease
- Acknowledgment of the multiple other factors influencing development of chronic kidney including hypertension and diabetes
- Showed awareness of limitations
Limitations/ negative aspects:
- Retrospective cohort study, inherently limited
- The coding of the types of congenital heart disease could be criticized: the category “all other heart and circulatory abnormalities” is too broad, there is also a huge spectrum of severity within the other categories.
- No information on the severity of CKD, how much impact does this diagnosis actually have? What percentage of congenital heart disease patients are on long term renal replacement therapy?
- Nephrotoxic drugs are not accounted for.
