globally the number of people living with hiv at advanced age is increasing . in 2013 , unaids estimated that 4.2 million people living with hiv were aged 50 and above . in sub - saharan africa which harbors more than seventy percent of all hiv cases , it was estimated that there were 2.4 million people living with hiv at the age 50 and above . projections show that this number will increase further and almost triple by the year 2030 . prolonged survival among hiv - infected patients following the use of art explains such an increase . however routine hiv testing is uncommon in this population , which makes them prone to late testing . highly active antiretroviral therapy ( haart ) has been shown to be effective in reducing hiv viral load , thereby improving cd4 lymphopenia . however the clinical and immunological responses in elderly patients treated with haart have been mixed . there is controversy about the rates of cd4 response among elderly patients compared to younger patients . while some studies have shown lower cd4 recovery among older patients [ 68 ] , others have not noted a significant difference in cd4 response between the two groups [ 911 ] . reports from sub - saharan africa which is the most affected region with hiv are scarce . this study aimed at assessing immunological and clinical responses following haart use among elderly hiv - infected patients . retrospective analysis of the data involving art nave patients initiating haart between 30th of june 2004 and 1st of may 2008 at sekou toure regional / referral hospital care and treatment clinic ( ctc ) in mwanza , northwestern tanzania , was done . haart was defined as a combination of two nucleoside reverse transcriptase inhibitors plus a nonnucleoside reverse transcriptase inhibitor or a protease inhibitor with or without a pharmacological booster . the age cut - off value was set at 50 years ( < 50 and 50 years old at baseline ) as used in other studies [ 6 , 12 , 13 ] . collected variables included the age at art initiation , sex , baseline cd4 cell count , who clinical stage at enrollment , occupation , marital status , type of first haart , indications for art , and time taken from art initiation to art change . late diagnosis was defined as presentation with who clinical stage 3 or 4 at the time of enrollment . immunological recovery was defined as cd4 cell count 350  cells / mm at 48 months of followup . data for this study were extracted from patient clinical files and data cleaning and descriptive data analysis was done using stata software version 12.0 ( statcorp , texas , usa ) . comparisons between the two groups were computed using chi - squared test for categorical variables , nonparametric wilcoxon rank - sum test for continuous variables , and student 's t - test to compare proportions between the groups and the comparison was considered significant at the p value less than 0.05 . a total of 728 patients were included in our study ; of these 73 ( 10.0% ) were aged 50 years and above . the median age was 37 ( iqr 3242 ) among younger patients and 54 ( iqr 5257 ) among the elderly patients . majority of participants were female in the younger group ( 69.9% ) and male in the elderly group ( 58.9% ) . comparisons of the baseline sociodemographic and clinical characteristics of the study participants are summarized in table 1 . late diagnosis was more common in elderly patients than young patients ( 65.7% versus 56.1% , p = 0.12 ) . median absolute increase in cd4 at 48 months was found to be significantly higher in younger patients than in their elderly counterpart ( + 241.5  cells / mm versus + 146  cells / mm , p = 0.007 ) . we also found the proportion of patients with cd4 count 350  cells / ul at the time of followup ( 48 months ) to be higher in the younger group ( 33.9% versus 30.1% , p = 0.2 ) . the median absolute increase in body weight was found to be similar between the two groups ( 5.0  kg versus 5.0  kg , p = 0.52 ) as was the proportion of patients who had a change in art regimen within the 48 months of followup ( 49.6% versus 38.4% , p = 0.06 ) . the proportion of patients who had opportunistic infection at 48 months was similar between the groups ( 4.6% versus 4.1% , p = 0.81 ) . this study aimed at assessing the immunological response following the use of art in hiv - infected patients aged 50 and above . out of 728 study participants , 73 ( 10% ) were aged 50 years and above . the age cut - off was set at 50 years as suggested in literature . after 48 months of followup , the absolute median increase in cd4 count was significantly lower in elderly patients than in younger patients . more patients in the younger group had attained cd4 of 350  cells / ul months of followup . proportions at 48 months of patients who changed art regimen during followup were more in elderly patients than in younger patients , although not significantly so . however , the median weight gain was comparable between the two groups . studies comparing the efficacy of art in elderly hiv - infected patients have been done elsewhere [ 10 , 1315 ] . similar to our findings , other studies also found immunological response to be decreasing with increasing age [ 8 , 16 ] . old age is also associated with reduced memory t cell populations , impaired t cell functionality , and reduced number of properly functioning cd8 cytotoxic t cells . the late testing in elderly patients has been described in other studies [ 15 , 20 , 21 ] . in our study , we also found that more elderly patients presented with hiv who clinical stages 3 and 4 diagnosed with advanced hiv ( who clinical stage 3 or 4 ) compared to younger patients . this is due to the fact that late presentation is also common in other age groups in sub - saharan africa as shown in other studies . late diagnosis has been associated with impaired immune response , clinical progression , and increased risk of mortality . more than half of the elderly patients ( 65.7% ) in our study presented with advanced hiv . other studies also found late presenters among elderly hiv - infected patients to be above 50% [ 12 , 21 , 22 ] . one of the reasons for late diagnosis could be the overlap between symptoms of hiv and those associated with ageing . clinicians are also high unlikely to suspect hiv in this population , something that may delay the diagnosis . analysis was based on data retrieved retrospectively from clinic database and patients ' files ; a lot of data was missing . some important parameters such as treatment adherence are not routinely documented during clinic visit and could not be analyzed despite its importance . this study was based on a single clinic ; the results may not necessarily be generalizable . in our study the missing data were equally distributed between groups and would not therefore be the reason for bias . to the best of our knowledge , this is the first study from tanzania reporting on immunological responses following the use of art among elderly hiv patients . the low immune response could be contributed by the late diagnosis of the disease which is more observed in elderly patients than younger patients in addition to the immunosenescence phenomena . we believe that our findings when coupled with the available guidelines for management of hiv patients have the potential to increase the rate of hiv testing with a subsequent early diagnosis and management . in addition , further studies are necessary to establish the long term outcome of these patients as well as the possibility of drug resistance .
background . 
 limited information exists on adults 50 years receiving hiv care in sub - saharan africa despite their increasing number . we aimed at studying immunologic and clinical responses to art in this population . 
 methods . 
 data of patients who initiated haart between 30th of june 2004 and 1st of may 2008 at sekou toure care and treatment clinic were retrospectively analyzed . 
 date of art initiation was used as a baseline and 48 months as a follow - up date . 
 immune recovery was defined as a cd4 count of 350 cells / mm3 at 48 months and late presentation as presentation with who stage 3 or 4 at clinic enrollment . 
 proportions of patients reaching this endpoint were compared between the two groups . 
 results . 
 a total of 728 patients were included in our study ; of these 73 ( 10.0% ) were aged 50 years and above . 
 late presentation was more common in elderly patients than young patients ( 65.7% versus 56.1% , p = 0.12 ) . 
 proportion of patients with cd4 count 350 ( immune recovery ) was higher in younger patients than in elderly patients , although this was not statistically significant ( 54.5% versus 44.9% , p = 0.2 ) . 
 median absolute increase in cd4 at 48 months was higher in younger patients than in elderly patients ( + 241.5 cells / mm3 versus + 146 cells / mm3 , p = 0.007 ) . 
 conclusion . 
 elderly hiv patients have higher rates of late presentation , with lower immune recovery . 
 strategies to increase hiv testing in this group are required for early diagnosis and treatment to improve outcomes .