P0173CHRONIC KIDNEY DISEASE IN PATIENTS WITH PRIMARY HYPEROXALURIA TYPE 3 (PH 3) - A LITERATURE META-ANALYSIS

Background and Aims Primary Hyperoxaluria type 3 (PH3) is considered the most benign phenotype of all forms of primary hyperoxaluria. Being it typical that patients with PH type 1 and 2 develop chronic kidney disease (CKD) or end-stage renal disease (ESRD), it appears to be more or less uncommon that patients with PH3 are on risk of CKD and even do not develop ESRD. We now aimed to determine the number of PH3 patients reported to have any kind of CKD. Method We performed a literature meta-analysis, searching in PubMed with the following keywords: primary hyperoxaluria, PH, primary hyperoxaluria type III, PH III or PH3. Results We found 154 patients in 18 relevant papers published between 2010-2019. The number of patients reported per paper ranged from 1-2 up to 38 patients. Age of diagnosis/disease onset ranged from 1 month to 48 years of life. Most of the patients suffered recurrent urolithiasis, most often during the first years of life, but recurrent kidney stone episodes were also found later in life. In 77 patients no adequate information was provided with regard to renal function. In 14 patients it was only mentioned that they did not have renal failure at time of reporting. Five patients were said to be in stable kidney function without providing eGFR or serum creatinine levels. In 62 patients we were able to assess kidney function at time of paper and only in 41 patients (27%) eGFR values were available (18-232 ml/min/1.73m2). Only one patient in ESRD was reported, however the clear reason for ESRD is not provided in the reference. One patient with CKD stage 4-5 was found with an eGFR of 18 ml/min/ 1.73m2, after heminephrectomy was performed due to renal carcinoma. He was diagnosed at age 78 but has had recurrent kidney stones over a period of 30 years. Other three patients had stage 2-3 kidney disease (eGFR 53-61.8 ml/min/1.73m2). CKD stages 1-2 were found in 17 patients (eGFR from 77-104 ml/min/1.73m2). In six patients follow-up measures were available, as their data were included in two papers (4 years apart from each other). Here, in one patient eGFR significantly declined from 134 to 68.1 ml/min/1.73m2, while in the other 5 it remained stable over time. Conclusion Based on this non-comprehensive dataset, the majority of PH3 patients remain in stable kidney function over time. However, there is a massive bias in the data published, as data on kidney function is mostly not adequately reported. Nevertheless, CKD was observed in 13.7% of PH3 patients, and even one patient with ESRD was described. Also, one PH3 patient had died at age 4 months, but because of respiratory failure and not because of PH. Thus, as true long-term follow-up data is still missing, we nevertheless suspect PH3 not being as benign as currently being reported.