Anemia is a prevalent public health issue worldwide that has a significant impact on health as well as socioeconomic development. The prevalence of anemia in China has been at a high level . In the current study, we examined the incidence and related elements of anemia in hospitalized people living with HIV in Guangxi, China. The results of our study showed the prevalence of anemia in the region to be 27.02%, and most of these patients were moderately anemic. The independent relevant elements for anemia were low CD4 count, females, and co-infection with PM, TB, or HCV.
The total prevalence of anemia in Guangxi, China was similar to previous studies in Ethiopia (23.1%) , Poland (25.2%) , and the USA (female: 24%, male: 28%) . The prevalence of anemia in the present study was lower compared to previous studies reported in Xinjiang, China (38.9%)  and Fujian, China (55.15%) . The possible causes are differences in demographics or different stages of HIV infection. However, in the current study, the prevalence of anemia among people living with HIV was greater than that previously reported in Beijing, China (9.8%) . This difference could be explained by the higher proportion of urban patients included and managed in a hospital-based setting , which is more likely to diagnose early anemia and take timely and effective action. Meanwhile, compared to rural subjects, urban subjects were likely to have obtained sufficient nutrition and better healthcare. In addition, most of the participants in the present study were in a state of deteriorating immune function, with 71.57% of patients having CD4 cell counts of < 200 cells/µL. The present study supports previous studies suggesting that anemia is prevalent in HIV-infected patients, with most patients in the moderate anemia stage.
There are relatively few studies on PM because it is endemic only in Southeast Asia and Southern China. Our findings indicated that the prevalence of anemia among HIV-infected patients co-infected with PM was 45.76%. Another retrospective study from Fujian Province, China explored 26 patients with PM infection hospitalized from September 2005 to April 2014 . The study was conducted to evaluate treatment and outcomes by comparing clinical data and laboratory parameters in people living with HIV and people living without HIV with PM infection. A total of 74% of patients with HIV co-infected with PM were anemic. Nevertheless, the included sample of the study was small which focused primarily on clinical symptoms in patients with PM infection and did not exclude potential confounding factors for anemia. Results showed that PM infection was a powerful individual factor associated with anemia in HIV-infected patients.
Anemia was more commonly seen in HIV-infected individuals with TB than in HIV-infected individuals without TB. Similar to the current findings, a study from southern India  showed a strong independent association between TB and anemia. Patients with TB were 1.6-fold more likely to be anemic compared to those who did not have TB. Chronic diseases such as TB are popular causes of anemia in HIV-infected patients . Furthermore, causes of TB-associated anemia include chronically infected  and nutritionally deficient  patients, thereby resulting in suppressed erythropoiesis. However, the etiology of TB-associated anemia in Chinese HIV-infected patients is not well understood as relevant laboratory examinations of red blood cells were not included in this study.
HIV and HCV co-infection is very common because of their similar transmission routes. HIV infection increases HCV viral load and may accelerate HCV disease progression . In the meantime, ribavirin (RBV), a drug frequently used to treat HCV infection, is known to induce hemolytic anemia . Maria Buti et al. reported that side effects of HIV co-infected with HCV during drug treatment include anemia, leukopenia, and depression . In our research, we found that HCV infection was one of the related factors for anemia and this was consistent with earlier studies. Nevertheless, the precise mechanisms causing anemia in patients co-infected with HIV and HCV remain to be further investigated.
Previous studies have reported that the causes of anemia in HIV-infected patients were diverse [6, 7, 29,30,31]. The current research findings indicated that a lower CD4 count was an independent correlate of anemia in HIV-infected patients. Our findings were consistent with studies reported in Uganda , USA , and Spain . In addition, the prevalence and severity of anemia increasing with a decrease in CD4 count was discovered. The relationship between CD4 counts and anemia is likely because of increased viral burden as the disease progresses, which may contribute to anemia through increased cytokine-mediated bone marrow suppression [6, 33]. Hence, we identified that the prevalence of OIs decreases as CD4 counts increase. Decreased CD4 counts indicate a loss of immunity in HIV-infected patients and that they may be more susceptible to OIs . Meanwhile, some of the OIs such as TB and PM may infiltrate the bone marrow to inhibit red blood cell production .
Current research showed that female patients were more prone to anemia than males. Findings were consistent with those previously published by Harding et al.  and Ferede et al.  Women's higher prevalence of anemia might be caused by menstrual blood loss, intrauterine devices (IUD) use, and so on . Meanwhile, the high prevalence of anemia in women is associated with malnutrition and nutritional deficiencies, including deficiencies of vitamin B12, folic acid, and iron [39, 40], which directly contribute to anemia.
In the present study, no association was found between anemia and age. However, Shen et al.  from China reported that increasing age was remarkably correlated with an increased risk of anemia, but did not correlate with gender. In contrast, Dai et al. found women and older age to be risk factors for anemia . However, the present study did not find a meaningful association between age and anemia in HIV-infected patients through logistic regression models. The main reason for the difference in findings may be the diverse age and gender distribution of the study samples. In addition, the geographical environment, economic conditions, medical policies, and dietary habits of the region under investigation can also affect the results of the study.
In conclusion, this study particularly assessed the relationship between anemia and OIs among hospitalized people living with HIV in Guangxi, China. The present research indicated that HCV, PM, TB, and being female were independently related elements for anemia in people living with HIV. Results confirmed and emphasized that OIs were independently related elements for anemia among HIV patients.
For the first time, the present study reported the correlation between anemia and OIs in HIV-infected patients in Guangxi, China. It also provided a statistical description of anemia and OIs in HIV-infected patients. The current study included a large sample size and was a good representation. Nevertheless, there are still some limitations of this study. First, most of the study population was sourced from Guangxi, China, and did not represent the full population of people living with HIV in China. Second, data were obtained from the electronic medical records of the hospital information system. This prevents us from elucidating the association between anemia and time-varying variables, therefore, the effect of treatment factors on anemia could not be observed. Third, the choice of a retrospective study approach in this study limited the explanation of the causality between anemia and associated factors in people living with HIV. Therefore, exploring the mechanisms of anemia in people living with HIV should be the next step.