Analysis of Nationwide Data to Determine the Incidence and Diagnosed Prevalence of Autosomal Dominant Polycystic Kidney Disease in the USA: 2013-2015

Epidemiology of Chronic Suppurative Otitis Media in the United States

OBJECTIVE

This study aimed to evaluate the prevalence, incidence, and associated demographic factors of chronic suppurative otitis media (CSOM), utilizing a nationwide healthcare claims database.

METHODS

This retrospective study utilized outpatient administrative claims data from the IBM MarketScan Research Database from 2007 to 2021. The database (11 246 909 584 claims with 148 147 615 unique patients) includes health data from the private-sector, Medicare/Medicaid, managed care providers, and EMR providers. Included patients had a diagnosis of CSOM based on ICD-9-CM and ICD-10-CM codes. Prevalence and health utilization were estimated by age, gender, and geographic region.

RESULTS

In the United States, the estimated CSOM prevalence and incidence was 0.46% and 0.03%, respectively. Among CSOM patients (n = 679 906), mean age (SD) was 8.1 (15.4) years, and 52.8% were male. Most patients (81.1%) were aged 0 to 10 years. CSOM prevalence was lower in females (OR = 0.64, 95% CI 0.64-0.65, P < .001), less common in older age (OR = 0.94, 95% CI 0.94-0.94, P < .001), and highest in the South region (OR = 2.08, 95% CI 2.06-2.09, P < .001).

CONCLUSION

Our results show CSOM prevalence (0.46%) is similar to other developed countries. CSOM prevalence was highest in those aged 0 to 10 years, in males and in the South region. Of note, prevalence and cost are likely significantly underestimated given limitations in accurate ICD-CM coding and the exclusion of uninsured patients. Further epidemiological studies are warranted to characterize the impact of CSOM on the US healthcare system.

Data driven approach to characterize rapid decline in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic kidney disease with high phenotypic variability. Furthering insights into patients' ADPKD progression could lead to earlier detection, management, and alter the course to end stage kidney disease (ESKD). We sought to identify patients with rapid decline (RD) in kidney function and to determine clinical factors associated with RD using a data-driven approach. A retrospective cohort study was performed among patients with incident ADPKD (1/1/2002-12/31/2018). Latent class mixed models were used to identify RD patients using differences in eGFR trajectories over time. Predictors of RD were selected based on agreements among feature selection methods, including logistic, regularized, and random forest modeling. The final model was built on the selected predictors and clinically relevant covariates. Among 1,744 patients with incident ADPKD, 125 (7%) were identified as RD. Feature selection included 42 clinical measurements for adaptation with multiple imputations; mean (SD) eGFR was 85.2 (47.3) and 72.9 (34.4) in the RD and non-RD groups, respectively. Multiple imputed datasets identified variables as important features to distinguish RD and non-RD groups with the final prediction model determined as a balance between area under the curve (AUC) and clinical relevance which included 6 predictors: age, sex, hypertension, cerebrovascular disease, hemoglobin, and proteinuria. Results showed 72%-sensitivity, 70%-specificity, 70%-accuracy, and 0.77-AUC in identifying RD. 5-year ESKD rates were 38% and 7% among RD and non-RD groups, respectively. Using real-world routine clinical data among patients with incident ADPKD, we observed that six variables highly predicted RD in kidney function.

Genotype-phenotype of autosomal dominant polycystic kidney disease in Malta

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the development of multiple renal cysts causing kidney enlargement and end-stage renal disease (ESRD) in half the patients by 60 years of age. The aim of the study was to determine the genetic aetiology in Maltese patients clinically diagnosed with ADPKD and correlate the clinical features.

METHODS

A total of 60 patients over 18 years of age clinically diagnosed with ADPKD were studied using a customized panel of genes that had sufficient evidence of disease diagnosis using next generation sequencing (NGS). The genes studied were PKD1, PKD2, GANAB, DNAJB11, PKHD1 and DZIP1L. Selected variants were confirmed by bidirectional Sanger sequencing with specifically designed primers. Cases where no clinically significant variant was identified by the customized gene panel were then studied by Whole Exome Sequencing (WES). Microsatellite analysis was performed to determine the origin of an identified recurrent variant in the PKD2 gene. Clinical features were studied for statistical correlation with genetic results.

RESULTS

Genetic diagnosis was reached in 49 (82%) of cases studied. Pathogenic/likely pathogenic variants PKD1 and PKD2 gene were found in 25 and in 23 cases respectively. The relative proportion of genetically diagnosed PKD1:PKD2 cases was 42:38. A pathogenic variant in the GANAB gene was identified in 1 (2%) case. A potentially significant heterozygous likely pathogenic variant was identified in PKHD1 in 1 (2%) case. Potentially significant variants of uncertain significance were seen in 4 (7%) cases of the study cohort. No variants in DNAJB11 and DZIP1L were observed. Whole exome sequencing (WES) added the diagnostic yield by 10% over the gene panel analysis. Overall no clinically significant variant was detected in 6 (10%) cases of the study population by a customized gene panel and WES. One recurrent variant the PKD2 c.709+1G > A was observed in 19 (32%) cases. Microsatellite analysis showed that all variant cases shared the same haplotype indicating that their families may have originated from a common ancestor and confirmed it to be a founder variant in the Maltese population. The rate of decline in eGFR was steeper and progression to ESRD was earlier in cases with PKD1 variants when compared to cases with PKD2 variants. Cases segregating truncating variants in PKD1 showed a significantly earlier onset of ESRD and this was significantly worse in cases with frameshift variants. Overall extrarenal manifestations were commoner in cases segregating truncating variants in PKD1.

CONCLUSIONS

This study helps to show that a customized gene panel is the first-line method of choice for studying patients with ADPKD followed by WES which increased the detection of variants present in the PKD1 pseudogene region. A founder variant in the PKD2 gene was identified in our Maltese cohort with ADPKD. Phenotype of patients with ADPKD is significantly related to the genotype confirming the important role of molecular investigations in the diagnosis and prognosis of polycystic kidney disease. Moreover, the findings also highlight the variability in the clinical phenotype and indicate that other factors including epigenetic and environmental maybe be important determinants in Autosomal Dominant Polycystic Kidney Disease.

Computational drug discovery approaches identify mebendazole as a candidate treatment for autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a rare genetic disorder characterised by numerous renal cysts, the progressive expansion of which can impact kidney function and lead eventually to renal failure. Tolvaptan is the only disease-modifying drug approved for the treatment of ADPKD, however its poor side effect and safety profile necessitates the need for the development of new therapeutics in this area. Using a combination of transcriptomic and machine learning computational drug discovery tools, we predicted that a number of existing drugs could have utility in the treatment of ADPKD, and subsequently validated several of these drug predictions in established models of disease. We determined that the anthelmintic mebendazole was a potent anti-cystic agent in human cellular and in vivo models of ADPKD, and is likely acting through the inhibition of microtubule polymerisation and protein kinase activity. These findings demonstrate the utility of combining computational approaches to identify and understand potential new treatments for traditionally underserved rare diseases.

Prospective Study on Individualized Dose Adjustment of Tolvaptan Based on Urinary Osmolality in Patients With ADPKD

Introduction

Tolvaptan has been shown to reduce renal volume and delay disease progression in autosomal-dominant polycystic kidney disease (ADPKD). However, no biomarkers are currently available to guide dose adjustment. We aimed to explore the possibility of individualized tolvaptan dose adjustments based on cut-off values for urinary osmolality (OsmU).

Methods

This prospective cohort study included patients with ADPKD, with rapid disease progression. Tolvaptan treatment was initiated at a dose of 45/15 mg and increased based on OsmU, with a limit set at 200 mOsm/kg. Primary renal events (25% decrease in estimated glomerular filtration rate [eGFR] during treatment), within-patient eGFR slope, and side effects were monitored during the 3-year follow-up.

Results

Forty patients participated in the study. OsmU remained below 200 mOsm/kg throughout the study period, and most patients required the minimum tolvaptan dose (mean dose, 64 [±10] mg), with a low discontinuation rate (5%). The mean annual decline in eGFR was -3.05 (±2.41) ml/min per 1.73 m2 during tolvaptan treatment, compared to the period preceding treatment, corresponding to a reduction in eGFR decline of more than 50%. Primary renal events occurred in 20% of patients (mean time to onset, 31 months; 95% confidence interval [CI] = 28-34).

Conclusion

Individualized tolvaptan dose adjustment based on OsmU in patients with ADPKD and rapid disease progression provided benefits in terms of reducing eGFR decline, compared with reference studies, and displayed lower dropout rates and fewer side effects. Further studies are required to confirm optimal strategies for the use of OsmU for tolvaptan dose adjustment in patients with ADPKD.

Prevalence and outcomes of polycystic kidney disease in African populations: A systematic review

BACKGROUND

Polycystic kidney disease (PKD) is the most common genetic cause of kidney disease. It is a progressive and irreversible condition that can lead to end-stage renal disease and many other visceral complications. Current comprehensive data on PKD patterns in Africa is lacking.

AIM

To describe the prevalence and outcomes of PKD in the African population.

METHODS

A literature search of PubMed, African journal online, and Google Scholar databases between 2000 and 2023 was performed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were followed to design the study. Clinical presentations and outcomes of patients were extracted from the included studies.

RESULTS

Out of 106 articles, we included 13 studies from 7 African countries. Ten of them were retrospective descriptive studies concerning 943 PKD patients with a mean age of 47.9 years. The accurate prevalence and incidence of PKD were not known but it represented the third causal nephropathy among dialysis patients. In majority of patients, the diagnosis of the disease was often delayed. Kidney function impairment, abdominal mass, and hypertension were the leading symptoms at presentation with a pooled prevalence of 72.1% (69.1-75.1), 65.8% (62.2-69.4), and 57.4% (54.2-60.6) respectively. Hematuria and infections were the most frequent complications. Genotyping was performed in few studies that revealed a high proportion of new mutations mainly in the PKD1 gene.

CONCLUSION

The prevalence of PKD in African populations is not clearly defined. Clinical symptoms were almost present with most patients who had kidney function impairment and abdominal mass at the diagnostic. Larger studies including genetic testing are needed to determine the burden of PKD in African populations.

Development and Validation of a Nomogram for Renal Survival Prediction in Patients with Autosomal Dominant Polycystic Kidney Disease

Introduction

Due to the wide variation in the prognosis of autosomal dominant polycystic kidney disease (ADPKD), prediction of risk of renal survival in ADPKD patients is a tough challenge. We aimed to establish a nomogram for the prediction of renal survival in ADPKD patients.

Methods

We conducted a retrospective observational cohort study in 263 patients with ADPKD. The patients were randomly assigned to a training set (N = 198) and a validation set (N = 65), and demographic and statistical data at baseline were collected. The total kidney volume was measured using stereology. A clinical prediction nomogram was developed based on multivariate Cox regression results. The performance and clinical utility of the nomogram were assessed by calibration curves, the concordance index (C-index), and decision curve analysis (DCA). The nomogram was compared with the height-adjusted total kidney volume (htTKV) model by receiver operating characteristic curve analysis and DCA.

Results

The five independent factors used to construct the nomogram for prognosis prediction were age, htTKV, estimated glomerular filtration rate, hypertension, and hemoglobin. The calibration curve of predicted probabilities against observed renal survival indicated excellent concordance. The model showed very good discrimination with a C-index of 0.91 (0.83-0.99) and an area under the curve of 0.94, which were significantly higher than those of the htTKV model. Similarly, DCA demonstrated that the nomogram had a better net benefit than the htTKV model.

Conclusion

The risk prediction nomogram, incorporating easily assessable clinical parameters, was effective for the prediction of renal survival in ADPKD patients. It can be a useful clinical adjunct for clinicians to evaluate the prognosis of ADPKD patients and provide individualized decision-making.

Many lessons still to learn about autosomal dominant polycystic kidney disease

We are still learning the genetic basis for many rare diseases. Here we provide a commentary on the analysis of the genetic landscape of patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD), one of the most common genetic kidney diseases. Approaches including both phenotype first and genotype first allows some interesting and informative observations within this disease population. PKD1 and PKD2 are the most frequent genetic causes of ADPKD accounting for 78% and 15% respectively, whilst around 7-8% of cases have an alternative genetic diagnosis. These rarer forms include IFT140, GANAB, PKHD1, HNF1B, ALG8, and ALG9. Some previously reported likely pathogenic PKD1 and PKD2 alleles may have a reduced penetrance, or indeed may have been misclassified in terms of their pathogenicity. This recent data concerning all forms of ADPKD points to the importance of performing genetics tests in all families with a clinical diagnosis of ADPKD as well as those with more atypical cystic kidney appearances. Following allele identification, performing segregation analysis wherever possible remains vital so that we continue to learn about these important genetic causes of kidney failure.

Energetic landscape of polycystin channel gating

Members of the polycystin family (PKD2 and PKD2L1) of transient receptor potential (TRP) channels conduct Ca2+ and depolarizing monovalent cations. Variants in PKD2 cause autosomal dominant polycystic kidney disease (ADPKD) in humans, whereas loss of PKD2L1 expression causes seizure susceptibility in mice. Understanding structural and functional regulation of these channels will provide the basis for interpreting their molecular dysregulation in disease states. However, the complete structures of polycystins are unresolved, as are the conformational changes regulating their conductive states. To provide a holistic understanding of the polycystin gating cycle, we use computational prediction tools to model missing PKD2L1 structural motifs and evaluate more than 150 mutations in an unbiased mutagenic functional screen of the entire pore module. Our results provide an energetic landscape of the polycystin pore, which enumerates gating sensitive sites and interactions required for opening, inactivation, and subsequent desensitization. These findings identify the external pore helices and specific cross-domain interactions as critical structural regulators controlling the polycystin ion channel conductive and nonconductive states.

Polycystin Channel Complexes

Polycystin subunits can form hetero- and homotetrameric ion channels in the membranes of various compartments of the cell. Homotetrameric polycystin channels are voltage- and calcium-modulated, whereas heterotetrameric versions are proposed to be ligand- or autoproteolytically regulated. Their importance is underscored by variants associated with autosomal dominant polycystic kidney disease and by vital roles in fertilization and embryonic development. The diversity in polycystin assembly and subcellular distribution allows for a multitude of sensory functions by this class of channels. In this review, we highlight their recent structural and functional characterization, which has provided a molecular blueprint to investigate the conformational changes required for channel opening in response to unique stimuli. We consider each polycystin channel type individually, discussing how they contribute to sensory cell biology, as well as their impact on the physiology of various tissues.

Myofibroblast depletion reduces kidney cyst growth and fibrosis in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) involves the development and persistent growth of fluid filled kidney cysts. In a recent study, we showed that ADPKD kidney cyst epithelial cells can stimulate the proliferation and differentiation of peri-cystic myofibroblasts. Although dense myofibroblast populations are often found surrounding kidney cysts, their role in cyst enlargement or fibrosis in ADPKD is unclear. To clarify this, we examined the effect of myofibroblast depletion in the Pkd1RC/RC (RC/RC) mouse model of ADPKD. RC/RC;αSMAtk mice that use the ganciclovir-thymidine kinase system to selectively deplete α-smooth muscle actin expressing myofibroblasts were generated. Ganciclovir treatment for four weeks depleted myofibroblasts, reduced kidney fibrosis and preserved kidney function in these mice. Importantly, myofibroblast depletion significantly reduced cyst growth and cyst epithelial cell proliferation in RC/RC;αSMAtk mouse kidneys. Similar ganciclovir treatment did not alter cyst growth or fibrosis in wild-type or RC/RC littermates. In vitro, co-culture with myofibroblasts from the kidneys of patients with ADPKD increased 3D microcyst growth of human ADPKD cyst epithelial cells. Treatment with conditioned culture media from ADPKD kidney myofibroblasts increased microcyst growth and cell proliferation of ADPKD cyst epithelial cells. Further examination of ADPKD myofibroblast conditioned media showed high levels of protease inhibitors including PAI1, TIMP1 and 2, NGAL and TFPI-2, and treatment with recombinant PAI1 and TIMP1 increased ADPKD cyst epithelial cell proliferation in vitro. Thus, our findings show that myofibroblasts directly promote cyst epithelial cell proliferation, cyst growth and fibrosis in ADPKD kidneys, and their targeting could be a novel therapeutic strategy to treat PKD.

Health Disparities in Kidney Failure Among Patients With Autosomal Dominant Polycystic Kidney Disease: A Cross-Sectional Study

Rationale & Objective

Understanding potential differences in patterns of kidney failure among patients with autosomal dominant polycystic kidney disease (ADPKD) may provide insights into improving disease management. We sought to characterize patients with ADPKD and kidney failure across different race/ethnicities.

Study Design

Cross-sectional study.

Setting & Participants

Kaiser Permanente Southern California members diagnosed with ADPKD between January1, 2002, and December 31, 2018.

Exposure

ADPKD.

Outcome

Kidney failure, dialysis, or receipt of kidney transplant.

Analytical Approach

Differences in characteristics by race/ethnicity were assessed using analysis of variance F test and χ² test. To compare the range and distribution of the average age at onset of kidney failure by race/ethnicity and sex, we used box plots and confidence intervals. Multivariable logistic regression was used to estimate OR for kidney transplant.

Results

Among 3,677 ADPKD patients, 1,027 (27.3%) had kidney failure. The kidney failure cohort was comprised of Black (n=138; 30.7%), White (n=496; 30.6%), Hispanic (n=306; 24.7%), and Asian (n=87; 23.6%) patients. Hispanic patients had the youngest mean age of kidney failure onset (50 years) compared to Black (56 years) and White (57 years) patients. Black (44.2%; OR, 0.72) and Hispanic (49.7%; OR, 0.65) patients had lower rates of kidney transplantation compared to White (53.8%) patients. Preemptive kidney transplantations occurred in 15.0% of patients.

Limitations

Retrospective study design and possible misclassification of ADPKD cases. Kidney function calculations were based on equations incorporating race, potentially overestimating kidney function in African Americans. The study was conducted within a single, integrated health care system in 1 geographic region and may not be generalizable to all ADPKD patients.

Conclusions

Among a large diverse ADPKD population, we observed racial/ethnic differences in rates of kidney failure, age of kidney failure onset, and rates of kidney transplantation. Our real-world ADPKD cohort provides insight into racial/ethnic variation in clinical features of disease and potential disparities in care, which may affect ADPKD outcomes.

High-Resolution Computed Tomography of Cystic Lung Disease

The cystic lung diseases (CLD) are characterized by the presence of multiple, thin-walled, air-filled spaces in the pulmonary parenchyma. Cyst formation may occur with congenital, autoimmune, inflammatory, infectious, or neoplastic processes. Recognition of cyst mimics such as emphysema and bronchiectasis is important to prevent diagnostic confusion and unnecessary evaluation. Chest CT can be diagnostic or may guide the workup based on cyst number, distribution, morphology, and associated lung, and extrapulmonary findings. Diffuse CLD (DCLDs) are often considered those presenting with 10 or more cysts. The more commonly encountered DCLDs include lymphangioleiomyomatosis, pulmonary Langerhans' cell histiocytosis, lymphoid interstitial pneumonia, Birt-Hogg-Dubé syndrome, and amyloidosis/light chain deposition disease.

Clinical and genetic study of a Chinese family affected by both amyotrophic lateral sclerosis and autosomal dominant polycystic kidney disease

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by loss of the upper and lower motor neurons from the motor cortex, brainstem, and spinal cord. Most ALS cases are sporadic, with 5–10% having a positive family history. Autosomal dominant polycystic kidney disease (ADPKD) is a heritable renal disease that eventually results in end-stage kidney disease. PKD1 is the most prevalent causative gene for ADPKD, accounting for ~85% of cases. Both diseases are currently considered untreatable. In this study, we report a large family that includes 10 patients with ALS phenotype, 3 asymptomatic SOD1-H47R carriers, and 6 with the ADPKD phenotype. Using whole exome sequencing, we found a novel likely pathogenic variant (p.R2787P) in PKD1 among patients with ADPKD, and a pathogenic variant (p.H47R) in SOD1 among patients with ALS. This study highlights the possibility that two different autosomal dominantly inherited diseases can co-exist independently within the same family. Phenotype—genotype correlations among these patients are also described. This research contributes novel phenotype and genotype characteristics of ALS with SOD1 mutations and ADPKD with PKD1 mutations.

Automated measurement of total kidney volume from 3D ultrasound images of patients affected by polycystic kidney disease and comparison to MR measurements

PURPOSE

Total kidney volume (TKV) is the most important imaging biomarker for quantifying the severity of autosomal-dominant polycystic kidney disease (ADPKD). 3D ultrasound (US) can accurately measure kidney volume compared to 2D US; however, manual segmentation is tedious and requires expert annotators. We investigated a deep learning-based approach for automated segmentation of TKV from 3D US in ADPKD patients.

METHOD

We used axially acquired 3D US-kidney images in 22 ADPKD patients where each patient and each kidney were scanned three times, resulting in 132 scans that were manually segmented. We trained a convolutional neural network to segment the whole kidney and measure TKV. All patients were subsequently imaged with MRI for measurement comparison.

RESULTS

Our method automatically segmented polycystic kidneys in 3D US images obtaining an average Dice coefficient of 0.80 on the test dataset. The kidney volume measurement compared with linear regression coefficient and bias from human tracing were R² = 0.81, and - 4.42%, and between AI and reference standard were R² = 0.93, and - 4.12%, respectively. MRI and US measured kidney volumes had R² = 0.84 and a bias of 7.47%.

CONCLUSION

This is the first study applying deep learning to 3D US in ADPKD. Our method shows promising performance for auto-segmentation of kidneys using 3D US to measure TKV, close to human tracing and MRI measurement. This imaging and analysis method may be useful in a number of settings, including pediatric imaging, clinical studies, and longitudinal tracking of patient disease progression.

Translating Clinical Research to Clinical Care in Nephrology: A Qualitative Study of Nephrology Clinicians

Rationale & Objective

Study Design

Setting & Participants

Analytical Approach

Results

Limitations

Conclusions

Screening of unruptured intracranial aneurysms in 50 to 60-year-old female smokers: a pilot study

The prevalence of unruptured intracranial aneurysms (UIAs) is around 2-3% in the general population. We hypothesized that the prevalence of small UIAs is higher among 50 to 60-year-old female smokers, since the incidence of aneurysmal subarachnoid hemorrhage (aSAH) is exceptionally high in 60 to 70-year-old female smokers. Ethics approval for this pilot study of 50 women was obtained from the hospital ethics committee. In order to minimize recruitment bias, preliminary invitation letters were sent to 50 to 60-year-old women who were known to be active smokers. Those interested in participating were further informed about the study rationale and protocol. Following written consent, participants filled a detailed questionnaire and underwent computed tomography angiography (CTA) analysis. All abnormalities were recorded. Of the 158 preliminary invitation letters, 70 potential participants initially replied. Of these, 50 returned questionnaires and written consents, 43 of which underwent CTA analysis. Most (39; 91%) were postmenopausal, and 9 (21%) were hypertensive. Two reported a family history (≥ 1 first-degree members) of intracranial aneurysms. UIAs (maximum sizes of 2, 2, 3, 3 and 7 mm) were found in five (12%) female smokers. One woman was operated on, and the remaining four were treated with non-invasive preventive actions (smoking cessation and follow-ups). Small UIAs, which may be best suited for non-invasive preventive actions, may be relatively common in 50 to 60-year-old female smokers. Whether this kind of targeted screening leads to improved health in female smokers requires further investigation.

Detection of Autosomal Dominant Polycystic Kidney Disease by Medical Checkup at an Early Stage

Introduction: Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disease. Although abdominal echography during medical checkup may be effective for the early detection of ADPKD, there are no reports of the early detection of ADPKD during medical checkup. We investigated whether there was a difference in renal function and total kidney volume (TKV) at the time of diagnosis due to differences in diagnostic triggers for ADPKD.

Methods: A total of 34 patients diagnosed with ADPKD between January 1, 2010, and December 31, 2020, at the Department of Nephrology, Shimane University Hospital, were included. The triggers for diagnosis of the renal cyst(s) were usually unintentional findings. These included findings observed upon routine medical checkups, computed tomography, or abdominal echography during examination for other diseases (incidental detection group) and cases referred to our department for renal dysfunction (renal dysfunction group), and “other” group. We compared the renal dysfunction group and the incidental detection group.

Results: The estimated glomerular filtration rate (eGFR) at diagnosis was significantly higher in the incidental detection group. The TKV was significantly lower in the incidental detection group than in the other group. The number of patients with eGFR > 45 mL/min/1.73 m², for which tolvaptan was safe and effective, was significantly higher in the incidental detection group than in the renal dysfunction group.

Conclusion: Our study shows that medical checkup enables early detection of ADPKD. This is important because ADPKD may have serious complications. The present study did not examine the age at which abdominal echography screening for the early detection of ADPKD was more useful or cost-effective; thus, further research is needed to ascertain this.

Autosomal Dominant Polycystic Kidney Disease Prevalence among a Racially Diverse United States Population, 2002 through 2018

Among a large racially and ethnically diverse US population, the prevalence of diagnosed ADPKD between 2002 and 2018 was 42.6 per 100,000 persons.ADPKD prevalence (per 100,000) was higher in (non-Hispanic) White (63.2) and Black (73.0) patients compared with Hispanic (39.9) and Asian (48.9) patients.Given the variable penetrance of ADPKD, our findings suggest race may be a factor in the clinical presentation and diagnosis of ADPKD.

Real-World Assessment of Interferon-β-1b and Interferon-β-1a Adherence Before and After the Introduction of the BETACONNECT® Autoinjector: A Retrospective Cohort Study

BACKGROUND

Both interferon beta-1b (IFN-β-1b) and interferon beta-1a (IFN-β-1a) are immunomodulators that require regular subcutaneous self-administration by patients with multiple sclerosis (MS). However, no electronic autoinjector is available for IFN-β-1a in the US.

OBJECTIVE

This retrospective cohort study investigated adherence to two subcutaneous disease-modifying therapies, IFN-β-1b and IFN-β-1a, during two periods (before and after the introduction of the BETACONNECT® autoinjector for IFN-β-1b).

PATIENTS AND METHODS

Data were evaluated from the MarketScan database for adults in the US with an MS diagnosis and a medical claim for subcutaneous IFN-β-1b or IFN-β-1a, either before (October 2013-September 2015) or after the introduction of BETACONNECT (October 2016-September 2018). Patient populations were propensity-score matched by demographic and clinical characteristics. Persistence was recorded, and adherence was evaluated by medication possession ratio (MPR).

RESULTS

The study included 196 IFN-β-1b and 365 IFN-β-1a people with MS (PwMS) (pre-BETACONNECT period), and 126 IFN-β-1b and 223 IFN-β-1a PwMS (post-BETACONNECT period). In the pre-BETACONNECT period, the proportion with at least 80% MPR was higher for IFN-β-1a (90%) than for IFN-β-1b (83%), but in the post-BETACONNECT period the proportion with ≥ 80% MPR was higher for IFN-β-1b (92%) than for IFN-β-1a (86%). In the pre-BETACONNECT period, median persistence (in days) was higher for IFN-β-1a (199) than for IFN-β-1b (152), while in post-BETACONNECT period persistence was higher for IFN-β-1b (327) than for IFN-β-1a (229).

CONCLUSIONS

Following the introduction of BETACONNECT, this exploratory study suggested that PwMS taking IFN-β-1b were more adherent compared with those taking IFN-β-1a, with higher persistence, and more than 90% reached 80% MPR, a threshold commonly used to define good adherence.

What are the information needs and concerns of individuals with Polycystic Kidney Disease? Results of an online survey using Facebook and social listening analysis

BACKGROUND

Polycystic Kidney Disease (PKD) is a hereditary disorder that has no cure and can result in end stage kidney failure. Searching for health information online and via social media is a common phenomenon in many medical conditions. However, no recent studies have documented the information needs, online behaviours, and concerns of people with PKD. The aim of this study was to explore the information needs of individuals with PKD and their carers by documenting (i) the information needs (ii) online information health seeking behaviours (iii) the perceived challenges of living with PKD and (iv) dietary concerns.

METHODS

A 17-item survey was constructed by undertaking a social listening analysis. This survey was then distributed via PKD related social media groups on Facebook. Seven groups distributed the survey with permission from the group owners. Open free text survey questions were analysed thematically using content analysis.

RESULTS

A total of 536 respondents completed the online survey (70.9 % female, 77 % aged 35-70, 70.2 % diagnosed more than 10 years ago). The major information need expressed by participants with PKD was for dietary information. Information regarding medications, medical management and symptom control were also desired. The overarching themes arising from the free text responses to the major challenge of living with PKD included 'learning to navigate dietary ambiguities'; 'managing social, psychological and emotional needs'; and 'accepting an uncertain future'. In addition to a strong desire for practical and specific dietary information, participants expressed a need for more online information pertaining to management of fatigue, pain, complications and how to manage mental health. Online peer support was also highly regarded and desired.

CONCLUSIONS

This study provides contemporary insights into the type of information desired by people with PKD. The results indicated that there was a strong desire for unambiguous information and guidance from health professionals to facilitate self-management, alleviate concerns, and address the complexities of living with Polycystic Kidney Disease. While diet is an important and frequently expressed need, there also remains a large demand for information on how to support psychological needs, and on medical management in order to support treatment decision making. Future work is required to develop specific, actionable and evidence-based resources for patients that are available online and through health professionals. Increased access to renal dietitians, peer support and additional training for health professionals could also improve patient-centered care and support self-management.

Regional variations in prevalence and severity of autosomal dominant polycystic kidney disease in the United States

OBJECTIVES

To evaluate geographic variation in the prevalence of autosomal dominant polycystic kidney disease (ADPKD) in the US, including ADPKD at risk of rapid progression.

METHODS

Claims data from the IBM MarketScan Commercial and Medicare Supplemental databases (01/16/2016-12/31/2017) were used to estimate the 2017 annual and 2016-2017 two-year prevalence of diagnosed ADPKD and ADPKD at risk of rapid progression in the US overall, and stratified by census regions and states. Risk of rapid progression was identified based on either: hypertension <35 years, hematuria <30 years, albuminuria, stage 2 chronic kidney disease (CKD) <30 years, stage 3 CKD <50 years, and stage 4/5 CKD or kidney transplant <55 years.

RESULTS

Annual prevalence was estimated at 2.34 and two-year prevalence at 3.61 per 10,000 in the US. Across census regions, two-year prevalence per 10,000 was highest in the Northeast (4.14) and lowest in the West (3.35). Prevalence was significantly correlated with the proportion of individuals in urban areas (r = .34, one-sided p = .026). In 2017, 37.5% of patients were identified as being at risk for rapid progression, and this proportion was larger among patients in the South (42.1%, p < .001).

CONCLUSION

This estimate for ADPKD prevalence is consistent with previously reported national estimates, with regional variation suggesting that ADPKD might be under-diagnosed in rural areas with more limited access to care. More than one-third of ADPKD patients presented risk factors associated with rapid progression, highlighting the need for timely identification, as disease-modifying therapy may delay progression to end-stage renal disease.

Increased risk of pulmonary and extrapulmonary tuberculosis infection in patients with polycystic kidney disease: a nationwide population-based study with propensity score-matching analysis

Background

Polycystic kidney disease (PKD) is a common renal disorder affecting approximately 1 in 1000 live births. Tuberculosis (TB) is an infectious disease worldwide. This study investigated the risk of TB infection in patients with PKD.

Methods

A nationwide population-based cohort study was performed using Taiwan’s National Health Insurance Research Database. We used patients’ hospitalization files for the entire analysis during 2000–2012. As per diagnosis, we divided patients into PKD and non-PKD cohorts and the major outcome was TB infection.

Results

A total of 13,540 participants with 6770 patients in each cohort were enrolled. The PKD cohort had a higher risk of TB infection than did the non-PKD cohort after adjusting for age, sex, and comorbidities (adjusted hazard ratio (aHR) = 1.91, 95% confidence interval [CI] = 1.51–2.43). When classifying by sites of pulmonary TB (PTB) and extrapulmonary TB (EPTB), the PKD cohort demonstrated a significantly higher risk of EPTB (aHR = 2.44, 95% CI = 1.46–4.08) as well as a risk of PTB (aHR = 1.69, 95% CI = 1.29–2.22). When stratified by the presence or absence of a comorbidity, high TB infection risk was noted in the PKD patients without any comorbidity (HR = 2.69, 95% CI = 1.69–4.30).

Conclusions

Taken together, our findings suggest that PKD is associated with a 1.91-fold increased risk of TB infection. Medical professionls should maintain a high index of suspicion in daily practice for patients with PKD, particularly those with EPTB infection.

Radiographic Imaging in Autosomal Dominant Polycystic Kidney Disease: A Claims Analysis

Background

Progression of autosomal dominant polycystic kidney disease (ADPKD) is highly variable, with some patients progressing rapidly to end-stage renal disease (ESRD). Abdominal imaging is an important modality for verifying diagnosis in patients at risk for rapidly progressing ADPKD, targeting them for early treatment that could slow onset of ESRD. Published literature is limited on the real-world abdominal imaging utilization patterns in ADPKD.

Methods

A retrospective healthcare administrative claims analysis examining abdominal imaging scans occurring from January 1, 2014, through June 30, 2017, was conducted using the IBM MarketScan^® commercial and Medicare supplemental databases. Patients in the United States who were at least 18 years old and had at least 1 inpatient claim or 2 outpatient claims (with different dates of service) with an ADPKD diagnosis code, as defined by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM codes 753.12 [polycystic kidney, unspecified type] and 753.13 [polycystic kidney, autosomal dominant] and/or Tenth Revision (ICD-10-CM codes Q61.2 [polycystic kidney, adult type] and Q61.3 [polycystic kidney, unspecified]) were included.

Results

Of the 4637 patients with ADPKD (mean age, 51.2 years [SD = 15.52]), 59% had ≥1 abdominal imaging scan. Of these patients, 46% had ≥1 computed tomography (CT) scan, 25% had ≥1 ultrasound, 10% had ≥1 magnetic resonance imaging scan. Among the 1754 patients (38%) with chronic kidney disease (CKD) stage information, CT imaging was more frequent in later stages (31% stage 1 versus 68% stage 5). The proportion of patients undergoing at least 1 CT or MRI scan increased with disease severity (37% in stage 1, 42% in stage 2, 48% in stage 3, 56% in stage 4, and 71% in stage 5).

Conclusion

Results of this analysis support the need for further investigation into abdominal imaging utilization in managing patients with ADPKD. Future research could clarify barriers and increase access to imaging, which has the potential to inform risk stratification, help patients delay dialysis or transplantation associated with ESRD, and help health systems avoid the costs associated with ESRD.

Cardiac Involvement in Autosomal Dominant Polycystic Kidney Disease

Cardiovascular disorders are the main complication in autosomal dominant polycystic kidney disease (ADPKD). contributing to both morbidity and mortality. This review considers clinical studies unveiling cardiovascular features in patients with ADPKD. Additionally, it focuses on basic science studies addressing the dysfunction of the polycystin proteins located in the cardiovascular system as a contributing factor to cardiovascular abnormalities. In particular, the effects of polycystin proteins’ deficiency on the cardiomyocyte function have been considered.

Disconnect in Assessments of Autosomal Dominant Polycystic Kidney Disease Burden Between Patients and Physicians: A Survey Study

Background

Autosomal dominant polycystic kidney disease (ADPKD) is a rare inherited kidney disorder with considerable symptom burden and negative effects even in early-stage disease. Patients' reporting of ADPKD symptom burden may differ from physicians' impressions. In this quantitative, cross-section survey study, we evaluated patient and physician assessments of symptom burden at early- and late-stage ADPKD.

Methods

In the United States, 300 patients with ADPKD and 155 physicians treating patients with ADPKD completed online surveys administered by Kantar. Disease stage was categorized as early (chronic kidney disease [CKD] stages 1-3) or late (stages 4-5). Patients completed the Work Productivity and Activity Impairment Questionnaire and reported current disease symptoms. Patients and physicians assessed impacts of ADPKD on daily life and burden of specific symptoms. Statistical analyses compared patient versus physician responses stratified by early- versus late-stage ADPKD.

Results

We found that impairment in work productivity was statistically greater in late- versus early-stage CKD. Compared with physicians' impressions, patients were more likely at early stages and less likely at later stages to report a moderate/strong impact of ADPKD on daily life. Among patients, 74% with early- and 88% with late-stage disease reported that ADPKD caused them to modify their daily lives. In early-stage disease, patients reported a statistically greater burden from feeling exhausted and less burden from dull kidney pain, cardiovascular problems, high blood pressure, and liver cysts than physicians assumed. At later stages, patients reported feeling exhausted and skeletal/joint pain as more burdensome, and frequent urination, high blood pressure, liver cysts, and hematuria as less burdensome, compared with physicians' impressions.

Conclusion

The results of this survey study demonstrate a disconnect between patients' experiences and physicians' awareness of the burden of ADPKD and highlight the need for more patient/physician discussion of symptoms and disease management.

Semantic Instance Segmentation of Kidney Cysts in MR Images: A Fully Automated 3D Approach Developed Through Active Learning

Total kidney volume (TKV) is the main imaging biomarker used to monitor disease progression and to classify patients affected by autosomal dominant polycystic kidney disease (ADPKD) for clinical trials. However, patients with similar TKVs may have drastically different cystic presentations and phenotypes. In an effort to quantify these cystic differences, we developed the first 3D semantic instance cyst segmentation algorithm for kidneys in MR images. We have reformulated both the object detection/localization task and the instance-based segmentation task into a semantic segmentation task. This allowed us to solve this unique imaging problem efficiently, even for patients with thousands of cysts. To do this, a convolutional neural network (CNN) was trained to learn cyst edges and cyst cores. Images were converted from instance cyst segmentations to semantic edge-core segmentations by applying a 3D erosion morphology operator to up-sampled versions of the images. The reduced cysts were labeled as core; the eroded areas were dilated in 2D and labeled as edge. The network was trained on 30 MR images and validated on 10 MR images using a fourfold cross-validation procedure. The final ensemble model was tested on 20 MR images not seen during the initial training/validation. The results from the test set were compared to segmentations from two readers. The presented model achieved an averaged R² value of 0.94 for cyst count, 1.00 for total cyst volume, 0.94 for cystic index, and an averaged Dice coefficient of 0.85. These results demonstrate the feasibility of performing cyst segmentations automatically in ADPKD patients.

Assessing Risk of Rapid Progression in Autosomal Dominant Polycystic Kidney Disease and Special Considerations for Disease-Modifying Therapy

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of kidney failure, accounting for 5%-10% of cases. Predicting which patients with ADPKD will progress rapidly to kidney failure is critical to assess the risk-benefit ratio of any intervention and to consider early initiation of long-term kidney protective measures that will maximize the cumulative benefit of slowing disease progression. Surrogate prognostic biomarkers are required to predict future decline in kidney function. Clinical, genetic, environmental, epigenetic, and radiologic factors have been studied as predictors of progression to kidney failure in ADPKD. A complex interaction of these prognostic factors determines the number of kidney cysts and their growth rates, which affect total kidney volume (TKV). Age-adjusted TKV, represented by the Mayo imaging classification, estimates each patient's unique rate of kidney growth and provides the most individualized approach available clinically so far. Tolvaptan has been approved to slow disease progression in patients at risk of rapidly progressive disease. Several other disease-modifying treatments are being studied in clinical trials. Selection criteria for patients at risk of rapid progression vary widely among countries and are based on a combination of age, baseline glomerular filtration rate (GFR), GFR slope, baseline TKV, and TKV rate of growth. This review details the approach in assessing the risk of disease progression in ADPKD and identifying patients who would benefit from long-term therapy with disease-modifying agents.

Excess healthcare costs in patients with autosomal dominant polycystic kidney disease by renal dysfunction stage

AIM

To build upon previous outdated studies by comprehensively assessing the direct healthcare burden of autosomal dominant polycystic kidney disease (ADPKD).

MATERIALS AND METHODS

Patients with ≥2 diagnoses for ADPKD (ADPKD cohort) were identified in the US fee-for-use IBM Truven Health Analytics MarketScan Commercial Claims and Encounters and IBM Truven Health Analytics MarketScan Medicare Supplemental databases (01 January 2015-31 December 2017) and matched (1:3) to controls without ADPKD (non-ADPKD cohort). The index date was the last calendar date followed by 12 months continuous enrollment (study period). Patients with ADPKD were stratified into one of seven mutually exclusive groups based on chronic kidney disease (CKD) stages (I-V), end-stage renal disease requiring renal replacement therapy (ESRD-RRT), and unknown stage.

RESULTS

During the 12-month study period, patients with ADPKD incurred significantly higher total healthcare costs than those without ADPKD (mean cost difference = $22,879 per patient per year [PPPY]; p < .001). Besides CKD stages I and II, total healthcare cost differences increased as patients progressed beyond CKD stage III, with the greatest difference observed among patients with ESRD-RRT. Total healthcare cost differences between cohorts were more pronounced in subgroups of patients with hypertension ($29,347) and with high risk of rapid progression ($39,976). Similar results were observed in the Medicare Supplemental population, with a total mean cost difference of $42,694 PPPY (p < .001); cost difference was also higher in the hypertension ($46,461 PPPY) and high risk of rapid progression ($45,708 PPPY) subgroups.

LIMITATIONS

Results may not be representative of the overall ADPKD US population; CKD stage was based on diagnosis and procedure codes; criteria used to identify ADPKD at risk of rapid progression did not rely on laboratory values; there may be billing inaccuracies and omissions in health insurance claims data.

CONCLUSIONS

This study demonstrated the substantial healthcare costs associated with ADPKD, which increased as patients progressed through more severe CKD stages.

Autosomal dominant polycystic kidney disease and pioglitazone for its therapy: a comprehensive review with an emphasis on the molecular pathogenesis and pharmacological aspects

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited chronic kidney disorder (CKD) that is characterized by the development of numerous fluid-filled cysts in kidneys. It is caused either due to the mutations in the PKD1 or PKD2 gene that encodes polycystin-1 and polycystin-2, respectively. This condition progresses into end-stage renal disorder if the renal or extra-renal clinical manifestations remain untreated. Several clinical trials with a variety of drugs have failed, and the only Food and Drugs Administration (FDA) approved drug to treat ADPKD to date is tolvaptan that works by antagonizing the vasopressin-2 receptor (V2R). The pathology of ADPKD is complex and involves the malfunction of different signaling pathways like cAMP, Hedgehog, and MAPK/ERK pathway owing to the mutated product that is polycystin-1 or 2. A measured yet substantial number of preclinical studies have found pioglitazone to decrease the cystic burden and improve the renal function in ADPKD. The peroxisome proliferator-activated receptor-gamma is found on the epithelial cells of renal collecting tubule and when it gets agonized by pioglitazone, confers efficacy in ADPKD treatment through multiple mechanisms. There is only one clinical trial (ongoing) wherein it is being assessed for its benefits and risk in patients with ADPKD, and is expected to get approval from the regulatory body owing to its promising therapeutic effects. This article would encompass the updated information on the epidemiology, pathophysiology of ADPKD, different mechanisms of action of pioglitazone in the treatment of ADPKD with preclinical and clinical shreds of evidence, and related safety updates.

Targeting and therapeutic peptide-based strategies for polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by progressive cyst growth and is a leading cause of renal failure worldwide. Currently, there are limited therapeutic options available to PKD patients, and only one drug, tolvaptan, has been FDA-approved to slow cyst progression. Similar to other small molecule drugs, however, tolvaptan is costly, only moderately effective, and causes adverse events leading to high patient dropout rates. Peptides may mitigate many drawbacks of small molecule drugs, as they can be highly tissue-specific, biocompatible, and economically scaled-up. Peptides can function as targeting ligands that direct therapies to diseased renal tissue, or be potent as therapeutic agents themselves. This review discusses various aberrant signaling pathways in PKD and renal receptors that can be potential targets of peptide-mediated strategies. Additionally, peptides utilized in other kidney applications, but may prove useful in the context of PKD, are highlighted. Insights into novel peptide-based solutions that have potential to improve clinical management of PKD are provided.

Biological Efficacy and Safety of Niacinamide in Patients With ADPKD

INTRODUCTION

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst enlargement, leading to kidney failure. Sirtuin-1 is upregulated in ADPKD and accelerates disease progression by deacetylating p53. Niacinamide is a dietary supplement that inhibits sirtuins at high doses.

METHODS

We conducted an open-label, single-arm intervention trial (study 1, N = 10), and a randomized, double blinded, placebo-controlled trial (study 2, N = 36) to assess the biological activity and safety of niacinamide. Patients with ADPKD were given 30 mg/kg oral niacinamide or placebo, for 12 months. The primary endpoint was the ratio of acetylated p53 to total p53 protein in peripheral blood mononuclear cells (PBMCs).

RESULTS

There was no sustained effect of niacinamide on acetylated/total p53 in either study and no difference between placebo and niacinamide arms. There was no difference in the change in height-adjusted total kidney volume over 12 months between niacinamide and placebo. Niacinamide was generally well tolerated. The most common adverse effects were nausea, diarrhea, gastroesophageal reflux, headache, and acneiform rash but there was no difference in their incidence between niacinamide and placebo.

CONCLUSIONS

In conclusion, niacinamide is safe and well-tolerated in patients with ADPKD. However, we were unable to detect a sustained inhibition of sirtuin activity over 12 months of treatment, and there was no signal to suggest a beneficial effect on any efficacy measure.

Etiology and impact on outcomes of polycystic kidney disease in abdominal aortic aneurysm

PURPOSE

We investigated the etiology and impact on outcomes of polycystic kidney disease in patients with abdominal aortic aneurysm.

METHODS

Eight-hundred patients who underwent open (n = 603) or endovascular aortic repair (n = 197) were divided into three groups: no cyst (n = 204), non-polycystic kidney (n = 503), and polycystic kidney (≥ 5 cysts in the bilateral kidneys, n = 93). The characteristics and outcomes were compared among the groups.

RESULTS

In the polycystic kidney group, the age was increased and the proportions of patients with male sex, hypertension, and estimated glomerular filtration rate < 30 mL/min/1.73 m² were greater. The overall hospital mortality rates were similar. The incidence of acute kidney injury after elective open aortic repair was increased in the polycystic kidney group (12%, 17%, and 29%, P = 0.020). In the polycystic kidney group, 80 patients did not have renal enlargement or a family history of renal disease, while 13 (corresponding to 1.6% [13/800] of the overall patients), had renal enlargement, suggesting the possibility of hereditary polycystic kidney disease.

CONCLUSIONS

In our cohort, 1.6% of the patients with abdominal aortic aneurysm who underwent surgery were at risk of hereditary polycystic kidney disease. Polycystic kidney disease was associated with acute kidney injury after open aortic repair.

Role of the RNA-binding protein Bicaudal-C1 and interacting factors in cystic kidney diseases

Polycystic kidneys frequently associate with mutations in individual components of cilia, basal bodies or centriolar satellites that perturb complex protein networks. In this review, we focus on the RNA-binding protein Bicaudal-C1 (BICC1) which was found mutated in renal cystic dysplasia, and on its interactions with the ankyrin repeat and sterile α motif (SAM)-containing proteins ANKS3 and ANKS6 and associated kinases and their partially overlapping ciliopathy phenotypes. After reviewing BICC1 homologs in model organisms and their functions in mRNA and cell metabolism during development and in renal tubules, we discuss recent insights from cell-based assays and from structure analysis of the SAM domains, and how SAM domain oligomerization might influence multivalent higher order complexes that are implicated in ciliary signal transduction.