Risk of hip fracture associated with hepatitis C virus infection and hepatitis C/human immunodeficiency virus coinfection

The impact of common co-morbidities (as measured using the Charlson index) on hip fracture risk in elderly men: a population-based cohort study

We used a large population-based health care database to determine the impact of common co-morbidities on hip fracture risk amongst elderly men. We demonstrated that diabetes, chronic obstructive pulmonary disease, renal failure, HIV infection, dementia, and cerebrovascular disease are independent predictors of hip fracture, as is a Charlson score of ≥ 3.

INTRODUCTION

Risk factors for hip fractures in men are still unclear. We aimed to identify common co-morbidities (amongst those in the Charlson index) that confer an increased risk of hip fracture amongst elderly men.

METHODS

We conducted a population-based cohort study using data from the SIDIAP (Q) database. SIDIAP(Q) contains primary care and hospital inpatient records of a representative 30% of the population of Catalonia, Spain (>2 million people). All men aged ≥ 65 years registered on 1 January 2007 were followed up until 31 December 2009. Both exposure (co-morbidities in the Charlson index) and outcome (incident hip fractures) were ascertained using ICD codes. Poisson regression models were fitted to estimate the effect of (1) each individual co-morbidity and (2) the composite Charlson index score, on hip fracture risk, after adjustment for age, body mass index, smoking, alcohol drinking, and use of oral glucocorticoids.

RESULTS

We observed 186,171 men for a median (inter-quartile range) of 2.99 (2.37-2.99) years. In this time, 1,718 (0.92%) participants had a hip fracture. The following co-morbidities were independently associated with hip fractures: diabetes mellitus, chronic obstructive pulmonary disease (COPD), renal failure, HIV infection, dementia, and cerebrovascular disease. A Charlson score of ≥ 3 conferred an increased hip fracture risk.

CONCLUSION

Common co-morbidities including diabetes, COPD, cerebrovascular disease, renal failure, and HIV infection are independently associated with an increased risk of hip fracture in elderly men. A Charlson score of 3 or more is associated with a 50% higher risk of hip fracture in this population.

Towards hepatitis C eradication from the HIV-infected population

Around 10-15% of the 35 million people living with HIV worldwide have chronic hepatitis C virus (HCV) infection and are prone to develop liver-related complications. Exposure to HCV is almost universal among injecting drug users and is on the rise among homosexual men. Response to peginterferon-ribavirin therapy is generally lower in coinfection compared to HCV monoinfection. For this reason, the advent of direct-acting antivirals (DAA) is eagerly awaited for this population. The results of trials using DAA in coinfection show that treatment response rates are similar to those obtained in HCV monoinfection. Thus, HIV should no longer be considered as a "special" population, as long as antiretroviral therapy is given and drug interactions are taken into account. Envisioning HCV eradication from the HIV population faces major challenges ahead, including identification of the large number of undiagnosed individuals, and ensuring wide access to the best but often expensive HCV medications. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication".

Bones, Fractures, Antiretroviral Therapy and HIV

The course of HIV infection has been dramatically transformed by the success of antiretroviral therapy from a universally fatal infection to a manageable chronic disease. With these advances in HIV disease management, age-related comorbidities, including metabolic bone disease, have become more prominent in the routine care of persons living with HIV infection. Recent data have highlighted the role of HIV infection, initiation of antiretroviral therapy, and hepatitis C virus coinfection in bone mineral density loss and fracture incidence. Additionally, the underlying mechanism for the development of metabolic bone disease in the setting of HIV infection has received considerable attention. This review highlights recently published and presented data and synthesizes the current state of the field. These data highlight the need for proactive prevention for fragility fractures.

Hepatitis C co-infection and severity of liver disease as risk factors for osteoporotic fractures among HIV-infected patients

Osteoporosis is increasingly reported in the aging HIV-positive population, and co-infection with hepatitis C virus (HCV) may further increase the risk of osteoporosis. However, it remains unclear whether HCV-related increased fracture risk is a function of the severity of liver disease. We calculated the time-updated alanine aminotransferase to platelet ratio index (APRI) score (an indirect marker of hepatic fibrosis) in all HIV-infected patients enrolled in the Veterans Affairs' Clinical Case Registry between 1984 and 2009. The association between HCV co-infection and incident osteoporotic fracture (defined as closed wrist, vertebral, or hip fracture) was assessed in univariate and multivariate Cox survival models adjusting for traditional risk factors for osteoporosis and APRI score or the presence of cirrhosis. A total of 772 osteoporotic fractures were identified among 56,660 HIV-infected patients (98.1% male; 31.3% HCV co-infected; median age 44.0 years) contributing 305,237 patient-years of follow-up. Fracture rates were significantly higher among HIV/HCV patients than HIV-only patients (2.57 versus 2.07/1000 patient-years, relative risk = 1.24, p < 0.0001). In a Cox multivariable model including age, race, smoking, drug use, body mass index, and antiretroviral therapy, HCV co-infection remained an independent predictor of osteoporotic fractures after controlling for presence of cirrhosis (hazard ratio [HR] = 1.32; p <0.001) or APRI score (HR = 1.30; p = 0.003). Among HIV/HCV co-infected patients, cirrhosis strongly predicted osteoporotic fractures (HR = 1.65; 95% confidence interval [CI] 1.11-2.44; p = 0.012), but APRI score was a weaker predictor (HR = 1.008; 95% CI 1.002-1.014; p = 0.015). In conclusion, among HIV-infected patients, severity of liver disease partly explains the HCV-associated increased risk of osteoporotic fractures. Other determinants of this increased risk remain to be defined.

Optimizing treatment in HIV/HCV coinfection

Sustained virological response (SVR) to anti-hepatitis C virus (HCV) treatment is an outcome that can improve life expectancy in persons with human immunodeficiency virus (HIV) infection. Results of anti-HCV treatment are poor, and less than 50% of treated patients show SVR to peginterferon plus ribavirin combination therapy; in infections from HCV genotype 1 this proportion is less than 40%. Pilot studies have demonstrated that Boceprevir or Telaprevir in combination with peginterferon plus ribavirin are able to increase the SVR rate from 45% to 74% with Telaprevir, and from 26% to 61% with Boceprevir in persons never treated for hepatitis C. Interim data seem to indicate a high rate of HCV RNA undetectability on treatment also in patients without sustained response to peginterferon plus ribavirin. Both Telaprevir and Boceprevir have drug-drug interactions with antiretrovirals, and options for concurrent antiretroviral therapy are restricted. There are also several new anti-HCV drugs under study with the potential for more tolerable effective future regimens. The indication for treatment in a patient with HCV/HIV coinfection should take into account the priority of treatment, the probability of sustained response, the potential toxicities, the concurrent antiretroviral therapy options, the patient's motivation, and the sustainability of current and future therapies.

Potential role of Hedgehog pathway in liver response to radiation

Radiation-induced fibrosis constitutes a major problem that is commonly observed in the patients undergoing radiotherapy; therefore, understanding its pathophysiological mechanism is important. The Hedgehog (Hh) pathway induces the proliferation of progenitors and myofibroblastic hepatic stellate cells (MF-HSCs) and promotes the epithelial-to-mesenchymal transition (EMT), thereby regulating the repair response in the damaged liver. We examined the response of normal liver to radiation injury. Male mice were sacrificed at 6 weeks and 10 weeks after exposure to a single dose of 6 Gy and the livers were collected for biochemical analysis. Irradiated (IR) and control mice were compared for progenitors, fibrosis, Hh pathway, and EMT at 6 and 10 weeks post irradiation. Fatty hepatocytes were observed and the expressions of Hh ligand, Indian Hh. were greater in the livers at 6 weeks, whereas expression of another Hh ligand, Sonic Hh, increased at 10 weeks post irradiation. Both Smoothened, Hh receptor, and Gli2, Hh-target gene, were up-regulated at 6 and 10 weeks after irradiation. Accumulation of progenitors (CD44, Pan-cytokeratin, and Sox9) was significant in IR livers at 6 and 10 weeks. RNA analysis showed enhanced expression of the EMT-stimulating factor, tgf-β, in the IR livers at 6 weeks and the upregulation of mesenchymal markers (α-SMA, collagen, N-cadherin, and s100a4), but down-regulation of EMT inhibitors, in IR mouse livers at 6 and 10 weeks. Increased fibrosis was observed in IR mouse livers at 10 weeks. Treatment of mice with Hh inhibitor, GDC-0449, suppressed Hh activity and block the proliferation of hepatic progenitor and expression of EMT-stimulating genes in irradiated mice. Therefore, those results demonstrated that the Hh pathway increased in response to liver injury by radiation and promoted a compensatory proliferation of MF-HSCs and progenitors, thereby regulating liver remodeling.

Incident fractures in HIV-infected individuals: a systematic review and meta-analysis

OBJECTIVE(S)

Some but not all studies indicate that individuals with HIV infection are at an increased risk of fracture. We systematically reviewed the literature to investigate whether incidence of fracture (both overall and fragility) differs between individuals with and without HIV.

DESIGN

A systematic review and meta-analysis.

METHODS

Medline, Scopus and the Cochrane Library databases for all studies ever published up to 28 September 2012 and electronically available conference abstracts from CROI, ASBMR, IAS and AIDS were searched. All studies reporting incidence of all fracture and fragility fracture in HIV-infected adults were included. A random effects model was used to calculate pooled estimates of incidence rate ratios (IRRs) for studies that presented data for HIV-infected and controls. For all studies, incidence rates of fracture and predictors of fracture among HIV-infected individuals were summarized.

RESULTS

Thirteen eligible studies were analysed, of which seven included controls. Nine studies reported all incident fractures and 10 presented incident fragility fractures. The pooled IRR was 1.58 [95% confidence interval (CI) 1.25-2.00] for all fracture and 1.35 (95% CI 1.10-1.65) for fragility fracture. Smoking, white race and older age were consistent predictors for fragility fractures.

CONCLUSION

Our results indicate that HIV infection is associated with a modest increase in incident fracture. Future research should focus on clarifying risk factors, designing appropriate interventions and the long-term implications of this increased risk for an ageing HIV-infected population.

Physiologic frailty and fragility fracture in HIV-infected male veterans

BACKGROUND

The Veterans Aging Cohort Study (VACS) Index is associated with all-cause mortality in individuals infected with human immunodeficiency virus (HIV). It is also associated with markers of inflammation and may thus reflect physiologic frailty. This analysis explores the association between physiologic frailty, as assessed by the VACS Index, and fragility fracture.

METHODS

HIV-infected men from VACS were included. We identified hip, vertebral, and upper arm fractures using ICD-9-CM codes. We used Cox regression models to assess fragility fracture risk factors including the VACS Index, its components (age, hepatitis C status, FIB-4 score, estimated glomerular filtration rate, hemoglobin, HIV RNA, CD4 count), and previously identified risk factors for fragility fractures.

RESULTS

We included 40 115 HIV-infected male Veterans. They experienced 588 first fragility fractures over 6.0 ± 3.9 years. The VACS Index score (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.11-1.19), white race (HR, 1.92; 95% CI, 1.63-2.28), body mass index (HR, 0.94; 95% CI, .92-.96), alcohol-related diagnoses (HR, 1.65; 95% CI, 1.26-2.17), cerebrovascular disease (HR, 1.95; 95% CI, 1.14-3.33), proton pump inhibitor use (HR, 1.87; 95% CI, 1.54-2.27), and protease inhibitor use (HR, 1.25; 95% CI, 1.04-1.50) were associated with fracture risk. Components of the VACS Index score most strongly associated with fracture risk were age (HR, 1.40; 95% CI, 1.27-1.54), log HIV RNA (HR, 0.91; 95% CI, .88-.94), and hemoglobin level (HR, 0.82; 95% CI, .78-.86).

CONCLUSIONS

Frailty, as measured by the VACS Index, is an important predictor of fragility fractures among HIV-infected male Veterans.

Fractures after antiretroviral initiation

BACKGROUND

Bone mineral density declines by 2-6% within 1-2 years after initiation of antiretroviral therapy (ART); however, it is uncertain whether this results in an immediate or cumulative increase in fracture rates.

METHODS

We evaluated the incidence and predictors of fracture in 4640 HIV-positive participants from 26 randomized ART studies followed in the AIDS Clinical Trials Group (ACTG) Longitudinal-Linked Randomized Trial study for a median of 5 years. Fragility and nonfragility fractures were recorded prospectively at semiannual visits. Incidence was calculated as fractures/total person-years. Cox proportional hazards models evaluated effects of traditional fracture risks, HIV disease characteristics, and ART exposure on fracture incidence.

RESULTS

Median (interquartile range) age was 39 (33, 45) years; 83% were men, 48% white, and median nadir CD4 cell count was 187 (65, 308) cells/μl. Overall, 116 fractures were reported in 106 participants with median time-to-first fracture of 2.3 years. Fracture incidence was 0.40 of 100 person-years among all participants and 0.38 of 100 person-years among 3398 participants who were ART naive at enrollment into ACTG parent studies. Among ART-naive participants, fracture rates were higher within the first 2 years after ART initiation (0.53/100 person-years) than subsequent years (0.30/100 person-years). In a multivariate analysis of ART-naive participants, increased hazard of fracture was associated with current smoking and glucocorticoid use but not with exposure to specific antiretrovirals.

CONCLUSION

Fracture rates were higher within the first 2 years after ART initiation, relative to subsequent years. However, continuation of ART was not associated with increasing fracture rates in these relatively young HIV-positive individuals.