The Prevalence of Cerebral Microbleeds in HIV-Infected Hemophilia Patients

Objective: Several studies have shown that rates of cerebrovascular events in HIV-infected patients are increased in comparison to uninfected individuals. In addition, cerebral bleeding represents a serious complication in hemophilia patients. Recently, asymptomatic cerebral microbleeds (CMBs), which can be detected by highly sensitive techniques such as T2*-weighted magnetic resonance imaging (MRI), have emerged as an important marker for predicting symptomatic cerebral bleeding. The aim of the present study was to investigate the prevalence of CMBs in HIVinfected hemophilia patients and to evaluate the association between HIV infection and cerebral bleeding. Methods: All HIV-infected hemophilia patients (HIV+ HemPts) who visited our hospital from January 2015 to December 2016 were enrolled in this study. In addition, all HIV-uninfected hemophilia patients (HIVHemPts) who visited our hospital in the same period were enrolled as controls. CMBs were assessed using T2*-weighted MRI. The relationship between cerebral bleeding and the patients’ clinical factors was examined. Results: Two HIV+ HemPts had symptomatic cerebral bleedings during the study period. Twenty-one asymptomatic HIV+ HemPts and 13 HIVHemPts underwent T2*-weighted MRI. CMBs were observed in 7 HIV+ HemPts (30.4%) and 1 HIVHemPts (7.7%). In the multivariate logistic regression analysis, HIV infection was the factor most closely related to cerebral bleeding (odds ratio: 9.78, p-value: 0.08). Conclusion: This is the first report to investigate the prevalence of CMBs in HIV-infected patients. The prevalence of CMBs or symptomatic cerebral bleeding in HIV+ HemPts was high in comparison to that in HIVHemPts. The brain screening test by T2*-weighted MRI seems to be meaningful for HIV+ HemPts. Citation: Endo T, Goto H, Miyashita N, Ara T, Kasahara K, et al. (2017) The Prevalence of Cerebral Microbleeds in HIV-Infected Hemophilia Patients. J AIDS Clin Res 8: 747. doi: 10.4172/2155-6113.1000747


Introduction
The development of antiretroviral therapy (ART) has increased the life expectancy of HIV-infected patients [1]. However, they continue to have a higher risk of death than HIV-uninfected individuals. This has been attributed to the increasing incidence of age-related diseases, such as cardiovascular diseases and cerebrovascular diseases. Several studies have shown that rates of cerebrovascular events in HIV-infected patients are increased in comparison to uninfected individuals [2][3][4][5]. Although cerebral bleeding is less frequent than cerebral ischemia in HIV-infected patients [4,6], it represents a serious complication, especially in HIVinfected hemophilia patients [7]. Therefore, predicting symptomatic cerebral bleeding is important to avoid complications.
The aim of the present study was to investigate the prevalence of CMBs in HIV-infected hemophilia patients and to evaluate the association between HIV infection and cerebral bleeding.

Patients
All HIV-infected adult hemophilia patients (HIV+ HemPts) who visited Hokkaido University Hospital from January 2015 to December 2016 were eligible to enroll in this study. In addition, all HIV-uninfected adult hemophilia patients (HIV-HemPts) who visited in the same period were also enrolled as controls. We excluded patients with metal implants or claustrophobia, which were thought to be contraindications for MRI. This study was performed in accordance with institutional ethical guidelines, including the World Medical Association Declaration of Helsinki and all patients gave their informed consent. For each patient, information was collected on the severity of hemophilia (severe vs mild-moderate), presence of coagulation factor inhibitor, prophylactic use of coagulation factor concentrate, viral infection (HBV or HCV), platelet count and cerebrovascular risk profile (diabetes mellitus, hyperlipidemia, hypertension, smoking habit).

MRI
CMBs were assessed using T2*-weighted MRI, appearing as small

The Prevalence of Cerebral Microbleeds in HIV-Infected Hemophilia Patients
dots of signal loss. Cerebral aneurysms were also assessed using magnetic resonance angiography (MRA). All MRI reports were made by experienced radiologist. The relationship between cerebral bleeding and the patients' clinical factors, such as age, the severity of hemophilia, hepatitis virus and HIV infection statuses, hypertension, hyperlipidemia, diabetes mellitus and smoking habit was examined.

MRI parameters
MRI was performed using a 3.0-T unit (Discovery MR750w 3.0T; GE Health care, Milwaukee, WI, USA). We obtained T2*-weighted MR images of the whole brain using the following parameters

Statistical analyses
Statistical analyses were performed with the JMP software program version 13.0 (SAS Institute, Inc, Cary, NC, USA). Statistical comparisons were made between the HIV+ HemPts and HIV-HemPts groups using the Wilcoxon test for age and Fisher's exact test for other parameters. Univariate and multivariate logistic regression analyses were performed to determine the independent parameters associated with cerebral bleeding. Parameters with P-value < 0.5 in univariate regression analyses were included in multivariate regression analyses. All P-values were 2-sided and a P-value of 0.05 was used as the cutoff for statistical significance.

Patients' characteristics
Twenty-five HIV+ HemPts and 14 HIV-HemPts visited Hokkaido University Hospital in the study period. One HIV+ HemPt with metal implant, one HIV+ HemPt with claustrophobia and one HIV-HemPt who refused to participate in the study were excluded. Ultimately, 36 patients (23 HIV+ HemPts, 13 HIV-HemPts) were enrolled in the study. The characteristics of each group are listed in Table 1. All patients were male and the median age was 48.0 years old in the HIV+ HemPts group and 47.0 years old in the HIV-HemPts group. The number of patients who use coagulation factor concentrate prophylactically was higher in the HIV+ HemPts group (P=0.04), although the severity of hemophilia was not significantly different between the two groups. The prevalence of hepatitis C tended to be higher in the HIV+ HemPts group (P=0.07).

Brain MRI findings
Two HIV+ HemPts had symptomatic cerebral bleeding during the study period. CMBs detected by T2*-weighted MRI were observed in 7 (30.4%) of the 23 HIV+ HemPts and 1 (7.7%) of the 13 HIV-HemPts ( Table 2). Representative images of CMBs are shown in Figure 1

HIV-HemPts (n=13)
prevalence of the total cerebral bleeding (symptomatic bleeding or asymptomatic CMBs) tended to be high in the HIV+ HemPts group (P=0.06). Cerebral aneurysms detected by MRA were observed in 3 HIV+ HemPts but in no HIV-HemPts. The number of patients with abnormal findings on brain MRI (cerebral bleedings or aneurysms) was significantly higher in the HIV+ HemPts than in the HIV-HemPts (P=0.03).

Risk factors of cerebral bleedings
We examined the clinical factors associated with cerebral bleeding for all hemophilia patients in this study (Table 3). In the univariate and the multivariate logistic regression analyses, HIV infection was the factor most closely related to cerebral bleeding, though there was no statistical significance (P=0.07 and 0.08, respectively).

Discussion
Several studies have shown that rates of cardiovascular and cerebrovascular events in HIV-infected patients are increased in comparison to uninfected individuals [2][3][4]12,13]. Chow et al. showed that the incidence rate of symptomatic cerebral bleeding was 2.29 per 1,000 person-years in HIV-infected patients compared with 1.23 per 1,000 person-year in uninfected individuals [3].
With the development of MRI techniques, CMBs have emerged as an important maker of cerebral vessel disease. CMBs are detected as small, rounded, homogeneous areas of signal loss on T2*-weighted MRI, representing hemosiderin deposits and they are a result of minor blood leakage through damaged blood vessels [14]. They are not commonly seen on conventional MRI or computed tomography imaging. It has been reported that individuals who have CMBs are 4 to 50 times more likely to experience symptomatic cerebral bleeding than those who do not have CMBs [11,15]. Therefore, brain screening examinations by T2*-weighted MRI seem to be beneficial in some disease settings, such as in HIV-infected patients. However, no reports have investigated the prevalence of CMBs in HIV-infected patients so far.
CMBs can be seen even in the normal elderly population. The prevalence is reported to range from 3.1% to 7.7% and is associated with advanced age [10,[16][17][18]. Vernooij et al. investigated the prevalence of CMBs in the general population ≥ 60 years of age and showed that the prevalence of CMBs increased with age, from 17.8% in those 60-69 years of age to 38.3% in those ≥ 80 years of age [19]. Regarding hemophilia patients, Zanon et al. performed brain MRI in 44 adult patients with hemophilia and CMBs were detected in 3 patients (6.8%) [20]. These reports suggest that hemophilia is not associated with the development of CMBs. In our present study, the prevalence of CMBs in HIV+ HemPts was 30.4%. When cases with symptomatic cerebral bleeding were added, the prevalence of cerebral bleeding in HIV+ HemPts was raised to 39.1%. This is extremely high for the age group (median 48.0 years, range 36-66). In contrast, the prevalence of CMBs in HIV-HemPts was only 7.7%, which is roughly the same as in healthy individuals or hemophilia patients.
In this study, HIV infection was the factor most closely related to the development of cerebral bleeding in all hemophilia patients, although there was no statistical significance. Rasmussen et al. reported that injection drug abuse, a low CD4 count and exposure to abacavir were risk factors of cerebrovascular events in HIV-infected patients [4]. In our present study, there were no patients who abused injection drugs. The HIV load was undetectable in 21 patients (91.3%) and CD4 counts were not suppressed in the patients. Seven patients (30.4%) used abacavir, but exposure to abacavir was not associated with the presence of CMBs.
Asymptomatic cerebral aneurysms were observed in 3 HIV+ HemPts in this study but in no HIV-HemPts. This finding is compatible with previous reports [21][22][23]. In those reports, chronic inflammation caused by HIV itself or by opportunistic infections was thought to be responsible for vulnerabilities of blood vessels and related to the formation of cerebral aneurysms. All HIV+ HemPts in the present study had a long history of HIV infection, as they had been infected with HIV via blood coagulation factor concentrate in the 1980s. Therefore, long-term micro inflammation due to HIV may cause CMBs or cerebral aneurysms in HIV+ HemPts.
In the present study, the number of patients with abnormal findings on brain MRI (cerebral bleedings or aneurysms) was significantly higher in HIV+ HemPts than in HIV-HemPts (P=0.03). Although the small sample size limited the power of the analysis, these findings indicate that brain screening by MRI is beneficial for HIV+ HemPts. To prevent future symptomatic cerebral bleeding, we managed the blood pressure more strictly, re-evaluated hemophilia treatments and encouraged lifestyle improvements, such as smoking cessation, for patients in whom CMBs were detected by T2*-weighted MRI. Patients in whom cerebral aneurysms were detected by MRA were followed up intensively by a brain surgeon.

Conclusion
In conclusion, this is the first report to investigate the prevalence of CMBs in HIV-infected patients. The prevalence of CMBs in HIV+ Thrombocytopenia was defined as platelet count less than 100 x10 9 /L. HemPts was higher than in HIV-HemPts. The evaluation of CMBs on T2*-weighted MRI may help clinicians tailor their therapeutic decisions in these patents.