Human immune deficiency virus type 1 (HIV-1) infection remains the most common risk factor for the development of active and reactivation of latent tuberculosis (TB); on the other hand, TB is commonly known to accelerate the progression of HIV disease. Vitamin D has been shown to provide protection against tuberculosis, and its supplementation has also been shown to increase immunity.
The currently available data from studies in humans regarding the potential value of vitamin D as adjunctive therapy in mycobacterial infection (TB) remain conflicting. There is also limited and contradictory evidence about the effect of vitamin D on the immune system. Furthermore, many of these studies were done in the developed world.
Tanzania is faced with high burden of HIV and tuberculosis. Assessment data on vitamin D status in HIV and HIVTB were in short supply, especially the rural settings. When programmes are well planned, using locally relevant, up to date data, implementation is likely to be more effective than when international or national guidelines are followed without appropriate adaptation. We found reasonable and ethical to conduct this study investigating the interaction existed between vitamin D, calcium, parathyroid hormone, and CD4 cells count in HIV-1 monoinfected and HIV/TB co infected patients.
Methods: A cross sectional study using quantitative methods was conducted from July 2010 to January 2011 at Haydom Lutheran Hospital in rural Tanzania. A purposive sampling technique was used to recruit 159 subjects aged 5 years and above. A standard data abstraction tool was used to obtain required information from the patients’ files/database. Serum vitamin D concentrations were measured by competitive Radioimmunoassay (RIA).
The subjects mean (SD) age was 35.5 (11.3) years; 85 (53.5%) were female, and
71(44.7%), 41(25.8%), and 47(29.6%) were HIV, HIVTB and healthy controls respectively. Subjects enrolled during postharvest (Aug-Oct) season had significantly higher serum 25(OH)D compared to short rain season (Nov-Jan); (75.9 ± 20.8 vs. 64.6 ± 22.2, P = 0.034. Similarly subjects aged less than 25 yrs had higher level of serum 1, 25-(OH)2D than age groups 35 – 45 yrs and > 45 yrs; P = 0.043, 0.002 respectively. Overall hypovitaminosis D (serum 25-(OH)-D < 75nmol/l) was found in 60.4%.
Subjects with HIV infection had higher serum 25-(OH)-D concentration than HIVTB-coinfected subjects (77.2 ± 20.8 vs 63.2 ± 23.8); P = 0.003. We observed hypovitaminosis D in 78.6% (11/14) of the HIVTB coinfected patients and in 52.1% (37/71) of the HIV monoinfected patients; the odd ratio (OR) of hypovitaminosis D for HIVTB coinfected patients was 3.4 (95% CI: 0.9, 13.1), P = 0.08. Advanced Clinical HIV stage (three and four) was significantly associated with lower serum 1,25-(OH)2D concentration, P = 0.021 and 0.0013 respectively. Subjects with CD4 cells count less 200 had lower level of serum 1,25(OH)2D than subjects with CD4 200 – 500 cells/mm3, 137.6 ± 63.9 vs 199.7 ± 58.1, P = 0.05.
Both serum 25 (OH)D and 1,25 (OH)2D levels were higher in HIV positive patients not on ART compared with those on ART, but the difference did not reach statistical significance; 81.4 (20.5) vs 74.7 (20.7) nmol/l and 182.8 (67.1) vs 165.1 (75.5) pmol/l, P = 0.190, 0.323 respectively. However in both univariate and multivariate logistic regression analysis, hypovitaminosis D remained significantly higher among HIV patients on antiretroviral therapy (ART) compared to HIV patients not on ART, OR = 3.5 (95% CI; 1.1, 12.3). However this may be due to advanced disease.
Advanced HIV stage was associated with lower serum 1,25(OH)2D concentrations, possibly due to reduced hydroxylation of 25(OH)D to 1,25(OH)2D in the macrophages. Serum 25-(OH)-D concentration was higher in HIV monoinfected than HIVTB coinfected patients, and hence hypovitaminosis D was more common among HIVTB coinfected than HIV monoinfected but the difference was not statistically significant due to small sample size. Hypovitaminosis D was higher in HIV patients on antiretroviral therapy compared with patients not on ART.
In conclusion, hypovitaminosis D was more common in HIV and HIVTB patients. Both health professionals and policy makers should be aware of this common co-morbidity and act accordingly.