A consensus statement on the renal monitoring of Australian patients receiving tenofovir based antiviral therapy for HIV/HBV infection

Acquired disorders of phosphaturia: Beyond tumor-induced osteomalacia

Phosphate is an integral part of human cellular structure and function. Though most recognised disorders of phosphaturia are genetic in origin, phosphate loss due to acquired conditions is commonly encountered in clinical practice. Acquired hypophosphatemia is most commonly due to renal phosphate wasting and can produce significant morbidity. It also heralds future kidney damage, and continued exposure can lead to progressive kidney injury and potentially renal failure. These conditions are a diverse group of disorders with common shared mechanisms causing loss of phosphate in the urine. Renal phosphate loss can occur as an isolated entity or as a part of generalised proximal tubular dysfunction, i.e., Fanconi's syndrome. An insight into the pathophysiological mechanisms of acquired phosphaturia can help clinicians monitor their patients better and avoid potential harms.

Fanconi syndrome induced by the long-term use of tenofovir disoproxil fumarate: a case report and literature review

We present the case of a woman of 50 years of age who experienced widespread bone pain along with digestive symptoms, including nausea and vomiting. She had been prescribed tenofovir disoproxil fumarate (TDF) tablets for the treatment of hepatitis B. Laboratory testing revealed low circulating phosphorus and potassium concentrations and acidosis. A whole-body bone scan revealed abnormal bone metabolism. Rheumatologic and urologic conditions were ruled out, and therefore TDF-induced Fanconi syndrome (FS) and related bone pain was diagnosed. After the TDF was discontinued, the patient's symptoms and laboratory indices significantly improved. In this manuscript, we highlight the clinical manifestations of and laboratory test results associated with FS and summarize the cases of TDF-induced FS reported on PubMed between 2013 and 2022 to improve understanding of FS.

Predictors of renal impairment and proteinuria after commencement of antiretroviral therapy in a Zimbabwean HIV cohort

BACKGROUND

Renal disease prevalence varies widely amongst reported cohorts of people living with HIV (PLWHIV) in sub-Saharan Africa. Renal function testing is not routine in those commencing antiretroviral therapy (ART) in the region, however. Further data on renal disease prevalence and the change associated with ART use are therefore needed.

AIM

To explore changes in renal function and associated predictors after 1 year of ART in an adult cohort of PLWHIV from Zimbabwe.

METHODS

A retrospective analysis of patients who attended the Newlands Clinic between January 2007 and September 2019. Eligible patients were aged ≥18 years and had measures of serum creatinine at baseline and after 1 year of ART. Predictors of renal function change were assessed by multiple linear regression.

RESULTS

1729 patients were eligible for inclusion. Median age was 36 years (IQR 30-43) and 62.8% were female. After 1 year of ART, the proportion of patients with an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73² did not significantly change (2.0% vs. 1.2%; p = 0.094), but there was a decrease in the proportion of patients with proteinuria (11.0% vs. 5.6%; p < 0.001). Hypertension (B = -6.43; 95% CI -8.97 to -3.89; p < 0.001) and baseline proteinuria (B = -7.33; 95% CI -10.25 to -4.42; p < 0.001) were negative predictors of change in eGFR from baseline, whereas diabetes status was not associated (p = 0.476).

CONCLUSION

Proteinuria was common, but its prevalence halved after 1 year of ART. Screening for hypertension could be a simple way to identify patients at risk of renal function decline.

Hepatitis B virus (HBV) viral load, liver and renal function in adults treated with tenofovir disoproxil fumarate (TDF) vs. untreated: a retrospective longitudinal UK cohort study

BACKGROUND

Current clinical guidelines recommend treating chronic hepatitis B virus (HBV) infection in a minority of cases, but there are relatively scarce data on evolution or progression of liver inflammation and fibrosis in cases of chronic HBV (CHB) that do not meet treatment criteria. We aimed to assess the impact of TDF on liver disease, and the risk of renal impairment in treated CHB patients in comparison to untreated patients.

METHODS

We studied a longitudinal ethnically diverse CHB cohort in the UK attending out-patient clinics between 2005 and 2018. We examined TDF treatment (vs. untreated) as the main exposure, with HBV DNA viral load (VL), ALT, elastography scores and eGFR as the main outcomes, using paired tests and mixed effects model for longitudinal measurements. Additionally, decline of eGFR during follow-up was quantified within individuals by thresholds based on clinical guidelines. Baseline was defined as treatment initiation for TDF group and the beginning of clinical follow-up for untreated group respectively.

RESULTS

We included 206 adults (60 on TDF, 146 untreated), with a median ± IQR follow-up duration of 3.3 ± 2.8 years. The TDF group was significantly older (median age 39 vs. 35 years, p = 0.004) and more likely to be male (63% vs. 47%, p = 0.04) compared to the untreated group. Baseline difference between TDF and untreated groups reflected treatment eligibility criteria. As expected, VL and ALT declined significantly over time in TDF-treated patients. Elastography scores normalised during treatment in the TDF group reflecting regression of inflammation and/or fibrosis. However, 6/81 (7.4%) of untreated patients had a progression of fibrosis stage from F0-F1 to F2 or F3. There was no evidence of difference in rates or incidence of renal impairment during follow-up in the TDF vs. untreated group.

CONCLUSIONS

Risk of liver inflammation and fibrosis may be raised in untreated patients compared to those receiving TDF, and TDF may benefit a larger percentage of the CHB population.

Benefits and Limits of Antiretroviral Drug Monitoring in Routine Practice

BACKGROUND

HIV infection is a chronic disease for which therapeutic adherence and tolerance require particular attention.

OBJECTIVE

This study aimed to assess whether and when therapeutic drug monitoring (TDM) could be associated with a benefit in routine practice.

METHODS

All HIV-infected patients who underwent at least one TDM at the University Hospital of Dijon (France) between 1st January 2009 and 31st December 2012 were retrospectively included. Compliance with the recommendations, the results (antiretroviral concentrations), any subsequent therapeutic modifications, and the virological results at 4-8 months were analysed each time TDM was performed. TDM was defined as "practically relevant" when low or high antiretroviral concentrations led to a change in therapy.

RESULTS

Of the 571 patients who followed-up, 43.4% underwent TDM. TDM complying with recommendations (120 patients) was associated with a higher proportion of antiretroviral concentrations outside the therapeutic range (p=0.03). Antiretroviral treatment was modified after TDM in 22.6% of patients. Protease inhibitors, non-nucleoside reverse transcriptase inhibitors and raltegravir were more significantly modified when the measured concentration was outside the therapeutic range (p=0.008, p=0.05 and p=0.02, respectively). Overall, 11.7% of TDM was considered "practically relevant", though there was no significant correlation between subsequent changes in antiretroviral treatment and undetectable final HIV viral load.

CONCLUSION

TDM may be a useful tool in the management of HIV infection in specific situations, but the overall benefit seems moderate in routine practice. TDM cannot be systematic and/or a decision tool per se, but should be included in a comprehensive approach in certain clinical situations.

Contemporary issues and new challenges in chronic kidney disease amongst people living with HIV

Chronic kidney disease (CKD) is a comorbidity of major clinical significance amongst people living with HIV (PLWHIV) and is associated with significant morbidity and mortality. The prevalence of CKD is rising, despite the widespread use of antiretroviral therapy (ART) and is increasingly related to prevalent non-infectious comorbidities (NICMs) and antiretroviral toxicity. There are great disparities evident, with the highest prevalence of CKD among PLWHIV seen in the African continent. The aetiology of kidney disease amongst PLWHIV includes HIV-related diseases, such as classic HIV-associated nephropathy or immune complex disease, CKD related to NICMs and CKD from antiretroviral toxicity. CKD, once established, is often relentlessly progressive and can lead to end-stage renal disease (ESRD). Identifying patients with risk factors for CKD, and appropriate screening for the early detection of CKD are vital to improve patient outcomes. Adherence to screening guidelines is variable, and often poor. The progression of CKD may be slowed with certain clinical interventions; however, data derived from studies involving PLWHIV with CKD are sparse and this represent an important area for future research. The control of blood pressure using angiotensin converting enzyme inhibitors and angiotensin receptor blockers, in particular, in the setting of proteinuria, likely slows the progression of CKD among PLWHIV. The cohort of PLWHIV is facing new challenges in regards to polypharmacy, drug-drug interactions and adverse drug reactions. The potential nephrotoxicity of ART is important, particularly as cumulative ART exposure increases as the cohort of PLWHIV ages. The number of PLWHIV with ESRD is increasing. PLWHIV should not be denied access to renal replacement therapy, either dialysis or kidney transplantation, based on their HIV status. Kidney transplantation amongst PLWHIV is successful and associated with an improved prognosis compared to remaining on dialysis. As the cohort of PLWHIV ages, comorbidity increases and CKD becomes more prevalent; models of care need to evolve to meet the new and changing chronic healthcare needs of these patients.

Risk of Nephrotoxicity in Patients With Drug-Resistant Tuberculosis Treated With Kanamycin/Capreomycin With or Without Concomitant Use of Tenofovir-Containing Antiretroviral Therapy

BACKGROUND

The intersection of HIV and drug-resistant (DR) tuberculosis (TB) presents the challenge of managing convergent drug toxicities.

METHODS

We conducted a retrospective study of adult patients with DR-TB treated with a kanamycin/capreomycin-based (KM) regimen, with or without concomitant antiretroviral therapy (ART). We estimated the incidence of nephrotoxicity (defined as an increase in serum creatinine greater than 26.5 µmol, or an increase in serum creatinine to 1.5 times the baseline value, or a decline in glomerular filtration rate to less than 60 mL/min/1.73 m), and evaluated the association between reported drug use and nephrotoxicity using Kaplan-Meier plots.

RESULTS

A total of 215 patients with DR-TB were treated with a kanamycin/capreomycin-based regimen, with or without concomitant ART. The incidence rate of nephrotoxicity was 3.6 [95% confidence interval (CI): 1.4 to 7.3], 6.9 (95% CI: 5.2 to 9.0), and 12 (95% CI: 3.3 to 30.9) cases per 100 person-months of follow-up in the KM only group (n = 42), the KM + TDF (tenofovir disoproxil fumarate) group (n = 163), and the KM + Other ART group (n = 10), respectively. Using the KM only group as a reference, the hazard ratio was 2.06 (95% CI: 0.92 to 4.63) in the KM + TDF group, and 4.09 (95% CI: 1.17 to 14.25) in the KM + Other ART group. Advancing age was an independent predictor of nephrotoxicity (adjusted hazard ratio 1.29, 95% CI: 1.14 to 1.46).

CONCLUSIONS

Our findings provide evidence of a significant risk of nephrotoxicity during treatment with a kanamycin/capreomycin-based DR-TB regimen, with or without concurrent treatment with ART. This study lends further support to calls for the substitution of TDF during the intensive phase of DR-TB treatment and for close monitoring of renal function during DR-TB treatment, especially in settings where the use of kanamycin/capreomycin is unavoidable.

Adefovir accumulation and nephrotoxicity in renal interstitium: Role of organic anion transporters of kidney

Common characteristics of drug induced nephrotoxicity are renal tubular and interstitial injury. Many studies have only focused on renal tubular injury. However, less is known about the effects of drugs in the renal interstitium on the nephrotoxicity. The aim of this study was to investigate the pharmacokinetics of adefovir (ADV) and the nephrotoxicity in the renal interstitium. Rats were treated with ADV alone or in combination with probenecid for 1, 7, 14, or 28 days. The renal interstitial fluid was collected by renal microdialysis. The concentration of ADV was determined by HPLC-MS/MS. Nephrotoxicity was evaluated by biochemical parameters or histological analysis. The results showed that organic anion transporters (OATs) inhibitor probenecid significantly increased the area under concentration-time curves (AUC) and peak concentration (C_max) of ADV in the renal interstitium, while the clearance (CL) in the renal interstitium was decreased in the ADV plus probenecid group compared to the ADV groups. After long-term treatment, interstitial fibrosis was present in the ADV plus probenecid group, whereas no trace of that could be detected in the ADV groups. Furthermore, a decrease was observed in the expression of OATs/Oats, which was dependent upon the concentrations and time of ADV treatment. In conclusion, it is possible that ADV could be accumulated in the interstitium when Oats were inhibited, which could cause renal interstitial fibrosis. Simply reducing cell uptake in long-term treatment might not be an effective method to protect against chronic nephrotoxicity.

Prevalence of Chronic Kidney Disease and Poor Diagnostic Accuracy of Dipstick Proteinuria in Human Immunodeficiency Virus-Infected Individuals: A Multicenter Study in Japan

BACKGROUND

Chronic kidney disease (CKD) has become one of the common comorbid conditions affecting the human immunodeficiency virus (HIV) population. Human immunodeficiency virus-infected individuals are at increased risk of developing CKD, and they are likely to experience faster progression of renal dysfunction compared with HIV-uninfected individuals. Albuminuria represents not only kidney damage but also manifests metabolic syndrome and vascular dysfunction.

METHODS

We conducted a multicenter, cross-sectional study involving 2135 HIV-infected individuals in Japan to test the prevalence of CKD and proteinuria/albuminuria. Urine sample was analyzed by both dipstick test and albumin-to-creatinine ratio (ACR) assay. Chronic kidney disease was classified according to the Kidney Disease Outcomes Quality Initiative (K/DOQI) and Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. The diagnostic performance of dipstick test to detect albuminuria (ACR ≥30 mg/g) was evaluated.

RESULTS

The prevalence of CKD, evaluated by K/DOQI and KDIGO guidelines, was 15.8% and 20.4%, respectively. Age, total cholesterol level, prevalence of hypertension, diabetes mellitus, and hepatitis C infection tended to increase, whereas levels of hemoglobin, serum albumin, and CD4 cell count tended to decrease as CKD risk grades progressed. Proteinuria and albuminuria were present in 8.9% and 14.5% of individuals, respectively. Dipstick test ≥1+ to detect albuminuria had an overall sensitivity of 44.9% and specificity of 97.2%.

CONCLUSIONS

The KDIGO guideline may enable physicians to capture HIV-infected patients at increased risk more effectively. The sensitivity of dipstick proteinuria to detect albuminuria is so poor that it may not serve as an alternative in HIV-infected individuals.

Fanconi syndrome due to tenofovir disoproxil fumarate reversed by switching to tenofovir alafenamide fumarate in an HIV-infected patient

A case of tenofovir-induced Fanconi syndrome in a patient receiving antiretroviral therapy for HIV infection, with resolution of the related electrolyte abnormalities upon switch from tenofovir disoproxil fumarate to tenofovir alafenamide fumarate, is reported. Tenofovir alafenamide fumarate, a novel prodrug of tenofovir containing significantly lower doses of tenofovir than tenofovir disoproxil fumarate, has been associated with a favourable renal profile compared to tenofovir disoproxil fumarate. Generally, the rare complication of tenofovir disoproxil fumarate-induced Fanconi syndrome is managed by cessation of tenofovir. There are limited reports of the impact of a switch strategy from tenofovir disoproxil fumarate to tenofovir alafenamide fumarate, which may be necessary in patients unable to discontinue tenofovir.

Incidence of renal Fanconi syndrome in patients taking antiretroviral therapy including tenofovir disoproxil fumarate

The objective of this study was to determine the incidence and predictors of Fanconi Syndrome (FS) in a cohort of patients taking tenofovir disoproxil fumarate (TDF). Clinical records and laboratory investigations from patients receiving TDF between 2002 and 2016 were extracted. FS was defined as normoglycaemic glycosuria and proteinuria and at least one other marker of renal dysfunction. Regression analysis was performed with time to development of FS and the following covariates: ritonavir co-administration, age, gender, co-morbidities (hypertension, hyperlipidaemia, diabetes, viral hepatitis), CD4 cell count nadir and baseline eGFR. One thousand and forty-four patients received TDF without ritonavir and 398 patients with ritonavir. Thirteen cases of FS were identified with a mean duration of exposure of 55 months. The incidence of FS was 1.09/1000PY (0.54-1.63) of TDF exposure (without ritonavir) and 5.50/1000PY (3.66-7.33) of TDF-ritonavir co-administration (p=0.0057). The adjusted hazards ratio for ritonavir co-administration was 4.71 (1.37-16.14, p=0.014). Known risk factors for chronic kidney disease were not associated with development of FS. Ritonavir co-administration, but not other factors, is associated with a greater risk of FS. FS developed late. Known risk factors for chronic kidney disease and length of treatment are not useful for identifying patients most at risk of developing FS in patients taking TDF.

Screening and management practices for renal disease in the HIV-positive patient population of an inner metropolitan sexual health service

Renal disease is an important and commonly encountered co-morbidity in HIV infection. Despite this, few data are available concerning renal disease in this patient group. A retrospective review was conducted of all HIV-positive patients of an inner metropolitan sexual health service who attended from 1 August 2013 to 31 July 2014 for HIV management. One hundred eighty-eight HIV-positive patients attended the clinic during the study period. The majority were male (96%), Caucasian (70%) and 30-39 years of age (37%). There was a high prevalence of renal risk factors in the population, including potentially nephrotoxic antiretroviral therapy (61%), smoking (38%), hypertension (12%), dyslipidemia (11%) and hepatitis C co-infection (7%). In the previous year, measurements of estimated glomerular filtration rate were performed in all patients, but measurements of lipid profiles, urinary protein and serum phosphate were performed within the last year in only 48%, 33% and 30% of patients, respectively. These are the first comprehensive data regarding renal disease, associated risk factors and screening and management practices in the HIV-positive patient population of a specialized sexual health service in Australia. This patient population demonstrates a particularly high prevalence of risk factors for renal disease. Despite this, screening investigations were not performed as recommended. This represents a potential area to improve patient care.

Nephrotoxicity caused by oral antiviral agents in patients with chronic hepatitis B treated in a hospital for tropical diseases in Thailand

BACKGROUND

There is increasing concern about the potential for nephrotoxicity in patients with chronic hepatitis B (CHB) treated long-term with nucleotide analogs.

METHODS

We examined renal dysfunction and its associated risk factors in patients with CHB treated with antiviral regimens containing either nucleosides or nucleotide analogs. We undertook a retrospective cohort study from 2006 to 2014 at the Hospital for Tropical Diseases, Bangkok, Thailand, and analyzed the data of 102 patients with a median follow-up time of 44.5 months (range 4-101 months).

RESULTS

Seventy-three patients were treated with an antiviral regime containing a nucleoside analog, and 29 with a regime containing a nucleotide analog. Abnormally elevated serum creatinine concentration was observed in 12 patients (11.8 %) after 8 years of treatment. Thirty one percent of patients treated with nucleotide analogs had elevated serum creatinine levels and three of these patients (10.3 %) developed nephrotoxicity. In contrast, serum creatinine concentrations were elevated in three of the 73 patients treated with a nucleoside analog (4.1 %), and none developed nephrotoxicity. The incidence of renal dysfunction by the nucleotide analog regimen was cumulative, with 11.1, 21.0, 26.5 and 47.6 % of patients affected after 2, 4, 6 and 8 years, respectively. Univariate and multivariate analysis indicated that a nucleotide analog-based regimen significantly predicted renal dysfunction (odds ratio 10.5, 95 % confidence intervals 2.6-42.4, P <0.001).

CONCLUSION

The long-term use of nucleotide analogs increased the risk of nephrotoxicity in patients with CHB. Thus, the regular assessment of renal function is recommended for all patients with CHB, particularly those treated with a nucleotide analog.