Effects of a reduced dose of stavudine on the incidence and severity of peripheral neuropathy in HIV-infected adults in South Africa

Distal leg epidermal nerve fiber density as a surrogate marker of HIV-associated sensory neuropathy risk: risk factors and change following initial antiretroviral therapy

Distal leg epidermal nerve fiber density (ENFD) is a validated predictor of HIV sensory neuropathy (SN) risk. We assessed how ENFD is impacted by initiation of first-time antiretroviral therapy (ART) in subjects free of neuropathy and how it is altered when mitochondrial toxic nucleoside medications are used as part of ART. Serial changes in proximal thigh and distal leg ENFD were examined over 72 weeks in 150 Thai subjects randomized to a regimen of stavudine (d4T) switching to zidovudine (ZDV) at 24 weeks vs ZDV vs tenofovir (TDF) for the entire duration of study, all given in combination with nevirapine. We found individual variations in ENFD change, with almost equal number of subjects who decreased or increased their distal leg ENFD over 72 weeks and no relationship to nucleoside backbone or to development of neuropathic signs or symptoms. Lower baseline distal leg ENFD and greater increases in mitochondrial oxidative phosphorylation complex I (CI) activity were associated with larger increases in distal leg ENFD over 72 weeks. Distal leg ENFD correlated with body composition parameters (body surface area, body mass index, height) as well as with blood pressure measurements. Assessed together with a companion cross-sectional study, we found that mean distal leg ENFD in all HIV+ subjects was lower than in HIV- subjects but similar among HIV+ groups whether ART-naïve or on d4T with/without neuropathy/neuropathic symptoms. The utility of ENFD as a useful predictor of small unmyelinated nerve fiber damage and neuropathy risk in HIV may be limited in certain populations.

Prevalence, incidence and predictors of peripheral neuropathy in African adults with HIV infection within the DART trial

OBJECTIVES

We investigated the prevalence, incidence and predictors of new peripheral neuropathy episodes in previously untreated, symptomatic HIV-infected Ugandan/Zimbabwean adults initiating zidovudine-based antiretroviral therapy (ART).

DESIGN

An open-label, multicentre, randomized trial.

METHODS

Peripheral neuropathy was self-reported at 12-weekly clinic visits. Cox regression models (excluding participants reporting preexisting peripheral neuropathy at ART initiation), considered sex; pre-ART WHO stage, age and CD4(+) cell count; CD4(+) cell count versus no CD4(+) cell count monitoring; and time-updated CD4(+) cell count, weight and use of stavudine, isoniazid and didanosine.

RESULTS

Four hundred and twenty-one out of 3316(13%) patients reported preexisting peripheral neuropathy at ART initiation. Median (interquartile range, IQR) follow-up in 2895 participants without preexisting peripheral neuropathy was 4.9 (4.7-5.4) years. Three hundred and fifty-four (12%) took stavudine as first-line substitution and 518 (18%) took isoniazid during follow-up. Two hundred and ninety (11%) participants developed a new peripheral neuropathy episode, an incidence of 2.12 per 100 person-years. Eighteen (0.1%) had a grade 3/4 episode. Independent predictors of peripheral neuropathy were current stavudine use [adjusted hazard ratio (a)HR 4.16 (95% confidence interval, 95% CI 3.06-5.66], current isoniazid use [aHR 1.59 (95% CI 1.02-2.47)] and current didanosine use [aHR 1.60 (95% CI 1.19-2.14)]. Higher risks were independently associated with higher pre-ART weight [aHR (per+5 kg) 1.07 (95% CI 1.01-1.13)] and older age aHR (per 10 years older) 1.29 (95% CI 1.12-1.49), but there was no significant effect of sex (P = 0.13), pre-ART CD4(+) cell count (P = 0.91) or CD4(+) cell count monitoring (P = 0.73).

CONCLUSION

Current stavudine, didanosine or isoniazid use continue to increase peripheral neuropathy risks, as does older age and weight at ART initiation; however, we found no evidence of increased risk in women in contrast to previous studies. The incidence of peripheral neuropathy may now be lower in ART programmes, as stavudine and didanosine are no longer recommended. All patients receiving isoniazid, either as part of antituberculosis (TB) chemotherapy or TB-preventive therapy, should receive pyridoxine as recommended in national guidelines.

Genetic variation in iron metabolism is associated with neuropathic pain and pain severity in HIV-infected patients on antiretroviral therapy

HIV sensory neuropathy and distal neuropathic pain (DNP) are common, disabling complications associated with combination antiretroviral therapy (cART). We previously associated iron-regulatory genetic polymorphisms with a reduced risk of HIV sensory neuropathy during more neurotoxic types of cART. We here evaluated the impact of polymorphisms in 19 iron-regulatory genes on DNP in 560 HIV-infected subjects from a prospective, observational study, who underwent neurological examinations to ascertain peripheral neuropathy and structured interviews to ascertain DNP. Genotype-DNP associations were explored by logistic regression and permutation-based analytical methods. Among 559 evaluable subjects, 331 (59%) developed HIV-SN, and 168 (30%) reported DNP. Fifteen polymorphisms in 8 genes (p<0.05) and 5 variants in 4 genes (p<0.01) were nominally associated with DNP: polymorphisms in TF, TFRC, BMP6, ACO1, SLC11A2, and FXN conferred reduced risk (adjusted odds ratios [ORs] ranging from 0.2 to 0.7, all p<0.05); other variants in TF, CP, ACO1, BMP6, and B2M conferred increased risk (ORs ranging from 1.3 to 3.1, all p<0.05). Risks associated with some variants were statistically significant either in black or white subgroups but were consistent in direction. ACO1 rs2026739 remained significantly associated with DNP in whites (permutation p<0.0001) after correction for multiple tests. Several of the same iron-regulatory-gene polymorphisms, including ACO1 rs2026739, were also associated with severity of DNP (all p<0.05). Common polymorphisms in iron-management genes are associated with DNP and with DNP severity in HIV-infected persons receiving cART. Consistent risk estimates across population subgroups and persistence of the ACO1 rs2026739 association after adjustment for multiple testing suggest that genetic variation in iron-regulation and transport modulates susceptibility to DNP.

Neurology and the Global HIV Epidemic

The vast majority of people living with human immunodeficiency virus (HIV) infection reside in resource-limited settings. As compared with resource-rich settings, there are important differences in the epidemiology and outcomes of HIV infection in resource-limited settings. Nonetheless, little HIV neurology research occurs in these regions. We will first review clinical, epidemiological, and translational HIV neurology research originating from resource-limited settings. We will then discuss the barriers to conducting neurologic research, such as limited human resources, diagnostics, and access to medications. Finally, we will review existing initiatives to build capacity for research in resource-limited settings. Despite the barriers, there is growing interest in and opportunities for collaborative international neurologic research. Including diverse viral and human populations from across the globe in research opens possibilities for important implementation science, clinically oriented science, and basic science discoveries.

HIV-related neuropathy: current perspectives

Distal symmetric polyneuropathy (DSP) related to human immunodeficiency virus (HIV) is one of the most common neurologic complications of HIV, possibly affecting as many as 50% of all individuals infected with HIV. Two potentially neurotoxic mechanisms have been proposed to play a crucial role in the pathogenesis of HIV DSP: neurotoxicity resulting from the virus and its products; as well as adverse neurotoxic effects of medications used in the treatment of HIV. Clinically, HIV DSP is characterized by a combination of signs and symptoms that include decreased deep tendon reflexes at the ankles and decreased sensation in the distal extremities as well as paresthesias, dysesthesias, and pain in a symmetric stocking-glove distribution. These symptoms are generally static or slowly progressive over time, and depending on the severity, may interfere significantly with the patient's daily activities. In addition to the clinical picture, nerve conduction studies and skin biopsies are often pursued to support the diagnosis of HIV DSP. Anticonvulsants, antidepressants, topical agents, and nonspecific analgesics may help relieve neuropathic pain. Specifically, gabapentin, lamotrigine, pregabalin, amitriptyline, duloxetine, and high-dose topical capsaicin patches have been used in research and clinical practice. Further research is needed to elucidate the pathogenesis of HIV DSP, thus facilitating the development of novel treatment strategies. This review discusses the epidemiology, pathophysiology, clinical findings, diagnosis, and management of DSP in the setting of HIV.

Comparison of tenofovir, zidovudine, or stavudine as part of first-line antiretroviral therapy in a resource-limited-setting: a cohort study

BACKGROUND

Tenofovir (TDF) is part of the WHO recommended first-line antiretroviral therapy (ART); however, there are limited data comparing TDF to other nucleoside reverse transcriptase inhibitors in resource-limited-settings. Using a routine workplace and community-based ART cohort in South Africa, we assessed single drug substitution, HIV RNA suppression, CD4 count increase, loss-from-care, and mortality between TDF, stavudine (d4T) 30 mg dose, and zidovudine (AZT).

METHODS

In a prospective cohort study we included ART naïve patients aged ≥17 years-old who initiated ART containing TDF, d4T, or AZT between 2007 and 2009. For analysis of single drug substitutions we used a competing-risks time-to-event analysis; for loss-from-care, mixed-effect Poisson modeling; for HIV RNA suppression, competing-risks logistic regression; for CD4 count slope, mixed-effects linear regression; and for mortality, proportional hazards modeling.

RESULTS

Of 6,196 patients, the initial drug was TDF for 665 (11%), d4T for 4,179 (68%), and AZT for 1,352 (22%). During the first 6 months of ART, the adjusted hazard ratio for a single drug substitution was 2.3 for d4T (95% confidence interval [CI]: 0.27, 19) and 5.2 for AZT (95% CI: 1.1, 23), compared to TDF; whereas, after 6 months, it was 10 (95% CI: 5.8, 18) and 4.4 (95% CI: 2.5, 7.8) for d4T and AZT, respectively. Virologic suppression was similar by agent; however, CD4 count rise was lowest for AZT. The adjusted hazard ratio for loss-from-care, when compared to TDF, was 1.5 (95% CI: 1.1, 1.9) for d4T and 1.2 (95% CI: 1.1, 1.4) for AZT. The adjusted hazard ratio for mortality, when compared to TDF, was 2.7 (95% CI: 2.0, 3.5) and 1.4 (95% CI: 1.3, 1.5) and for d4T and AZT, respectively.

DISCUSSION

In routine care, TDF appeared to perform better than either d4T or AZT, most notably with less drug substitution and mortality than for either other agent.