Autosomal dominant polycystic kidney disease (APKD) is the most common heritable cause of kidney disease with well-described genetics. A recent study published in AJKD describes the epidemiology and incidence trends of ESRD due to APKD in the US.  Dr. Scott Reule, the first author, discusses the study with Dr. Paul Phelan (eAJKD), eAJKD Contributor.

eAJKD: Can you explain why you felt this topic was important?

SR: APKD serves as an excellent care model for CKD and ESRD given its early detection and opportunities for early management. Literature regarding clinical epidemiology is sparse. Moreover, the effect of non-disease specific interventions, such as hypertension management, on outcomes such as mortality, wait listing for transplantation, and receipt of a kidney transplant is unknown. Using CMS form 2728 data, we were able to review 23,772 patients with ESRD due to APKD in a retrospective, observational study.

eAJKD: Please summarize the major findings of the study?

SR: Compared to the baseline biennium, overall standardized incidence ratio (SIR) of APKD significantly increased in 2005-2006 (1.07) and 2007-2008 (1.06), returning to 1.02 in the most recent biennium. Stratified by age, there was a sustained increase in SIR over all biennia for those aged 40-64 years (1.11 in 2009-2010).

Associations with ESRD due to APKD adjusted for age, sex, race, and ethnicity included age 40-64 years, female sex, use of peritoneal dialysis at initiation, and receipt of preemptive kidney transplantation (living and deceased donor). Those with ESRD due to APKD were more likely to receive pre-dialysis nephrology care for >12 months prior to initiation (48.1% vs. 23.7%) and to utilize a fistula (35.8% vs. 13.4%).

Characteristics associated with the highest likelihood of survival included peritoneal dialysis as primary modality (adjusted HR 0.66), and receipt of a preemptive kidney transplant (AHR, LD 0.13; DD 0.21). Factors associated with the lowest likelihood of wait-listing and receipt of a kidney transplant included age ≥65 years (AHR 0.21) and presence diabetes and ischemic heart disease.

eAJKD: Recent trends in the US have been to initiate dialysis at higher eGFR. The IDEAL study (2010) has challenged the wisdom of this approach. Does your data from 2001-2010 shed any light on the trends for APKD, a group traditionally with less comorbidity?

SR: This is an excellent point and one in which we were very interested. In patients with ESRD due to APKD, it appears that those initiating dialysis in the most recent era (2006-2010) were more likely to initiate at an eGFR >15 mL/min/1.73m² (7.9% vs. 3.6%; adjusted OR 2.27). It is possible that the overall SIR trend may be somewhat attenuated by this finding, however given the non-APKD cohort demonstrated a decrease in ESRD in the most recent two biennia, it is disappointing to see that those with APKD did not experience a similar decrease. Regarding eGFR at initiation, it appears that this subgroup of relatively comorbidity-free dialysis patients may in fact experience worse outcomes with initiation at a higher eGFR. Those whom initiated RRT at an eGFR >15 mL/min/1.73m² appeared to have an increased risk of death with decreased likelihood of listing for (AHR 0.74) and receipt of a kidney transplant (AHR 0.73).

eAJKD: Do you think your study highlights any issues with pre-ESRD nephrology care in the US?

SR: While the metrics of optimal care in APKD were nearly double that of other causes, such as access other than a hemodialysis catheter and pre-RRT care duration, it is concerning that less than 50% of the APKD cohort received pre-RRT care >12 months. This area highlights a particular concern, as patient preparation for RRT and evaluation for transplantation may translate into improved patient level outcomes. Unfortunately, we are limited in determining whether this is truly the case, as this analysis is observational in nature.

eAJKD: Anything further you wish to add regarding the study?

SR: Some challenges we encountered included lack of specific imaging data, family histories, and registry limitations regarding ascertainment of vascular access and duration of pre-dialysis care, as the information was only captured in the 2005 version of the 2728 form. This information would be of significant interest in helping to validate the cohort and allow for analysis regarding clustering of cases and outcomes moving forward.

To view the article abstract or full-text (subscription required), please visit AJKD.org.