Progression of autosomal dominant kidney disease: measurement of the stage transitions of chronic kidney disease

Abstract

Background: Autosomal dominant polycystic kidney disease (ADPKD) is a progressive genetic disorder characterized by the development of numerous kidney cysts that result in kidney failure. Little is known regarding the key patient characteristics and utilization of healthcare resources for ADPKD patients along the continuum of disease progression. This observational study was designed to describe the characteristics of ADPKD patients and compare them with those of patients with other chronic kidney diseases.

Methods: This retrospective cohort study involved patients with a claim for ADPKD or PKD unspecified from 1/1/2000-2/28/2013 and ≥6 months of previous continuous enrollment (baseline) within a large database of administrative claims in the USA. A random sample of chronic kidney disease (CKD) patients served as comparators. For a subset of ADPKD patients who had only a diagnosis code of unspecified PKD, abstraction of medical records was undertaken to estimate the proportion of patients who had medical chart-confirmed ADPKD. In patients with linked electronic laboratory data, the estimated glomerular filtration rate was calculated via serum creatinine values to determine CKD stage at baseline and during follow-up. Proportions of patients transitioning to another stage and the mean age at transition were calculated.

Results: ADPKD patients were, in general, younger and had fewer physician visits, but had more specific comorbidities at observation start compared with CKD patients. ADPKD patients had a longer time in the milder stages and longer duration before recorded transition to a more severe stage compared with CKD patients. Patients with ADPKD at risk of rapid progression had a shorter time-to-end-stage renal disease than patients with CKD and ADPKD patients not at risk, but stage duration was similar between ADPKD patients at risk and those not at risk.

Conclusions: These results suggest that distribution of patients by age at transition to next stage may be useful for identification of ADPKD patients at risk of rapid progression. The results also suggest that medical claims with diagnosis codes for "unspecified PKD", in absence of a diagnosis code for autosomal recessive polycystic kidney disease, may be a good proxy for ADPKD.

Keywords: ADPKD; autosomal dominant polycystic kidney disease; chronic kidney disease; disease stage; end-stage renal disease; serum creatinine.

Figure 1.

Flow chart for the study. ADPKD, autosomal dominant polycystic kidney disease; ARPKD, autosomal recessive polycystic kidney disease; CKD, chronic kidney disease.

Figure 2.

Time-to-ESRD among ADPKD patients, CKD patients, and ADPKD patients at risk of rapid progression, overall^a. ^aFor the overall cohort, P<0.0001. ADPKD, autosomal dominant polycystic kidney disease; CKD, chronic kidney disease; ESRD, end-stage renal disease.

Figure 3.

Time-to-ESRD among ADPKD patients, CKD patients, and ADPKD patients at risk of rapid progression: baseline stage I (a), baseline stage II (b), baseline stage III (c), and baseline stage IV (d)^a. ^aBaseline stage I (a), P=0.0002; baseline stage II (b), P=0.7808; baseline stage III (c), P<0.0001; baseline stage IV (d), P<0.0001. ADPKD, autosomal dominant polycystic kidney disease; ESRD, end-stage renal disease; CKD, chronic kidney disease.