Time to Recurrence of any Opportunistic Infection after Treatment of it among People Living with HIV Infection in Debre Markos, Northwest Ethiopia: Retrospective Cohort study

The other problems among the HIV sero-positive individuals were dual and triple OIs and other co-infections; according to studies, the most frequent dual infections were chronic diarrhea and oral candidiasis (28.92%), oral candidiasis and TB (25.49%), chronic diarrhea and TB (21.08%), HSV-2 and oral candidiasis (19.11%), HSV2 and cytomegaly virus (14.21%), Hepatitis-B virus and HSV-2 (3.92%); the commonest triple infections were oral candidiasis, TB and chronic diarrhea (14.21%); HSV-2, CMV and oral candidiasis (10.78%); HSV-2, CMV and chronic diarrhea (8.34%); and HSV-2, CMV and TB (6.86%) [10].

Introduction of combination antiretroviral therapy in 1996 has led to dramatic reductions in morbidity and mortality from HIV/AIDS [1,2]. In Ethiopia, the fee based and universal free access antiretroviral (ARV) treatment was started in 2002/3 and 2004/5 respectively [5,6].
HIV infection leads to AIDS and major causes of morbidity and mortality of such patients are opportunistic infections (OIs) caused by viral, bacterial, fungal and parasitic pathogens [7]. OIs can occur in about 40% of people living with HIV (PLHIV) with a CD4 count less than 250/mm 3 [8].

Methods and Patients Study area, period and design
Debre Markos town has one referral hospital and one public health center, which provide ART service. The study was conducted in Debre Markos hospital and health center among 6261 adult PLHIV who were on chronic HIV care or ART follow up between 25 th March 2007 and 24 th March 2013. Institution-based retrospective cohort study was conducted from March 25 th 2007 to March 24 th using quantitative research method.

Source and study population
All 18 years old and above PLHIV infections having chronic HIV care or on ART follow up in Debre Markos town health institutions providing ART service were the source populations. All adult PLHIV infections that had developed any OI and on standard treatment in chronic HIV care or on ART follow up found in ART service providing health institutions in Debre Markos town were included in the study

Sampling and sample size determination
The sample size was calculated based on the assumption of 95% confidence interval and 80% power with ratio of one to one for ART and pre-ART PLHIV using the proportions of the commonest OI (TB) which were 6% and 14 % for ART and pre-ART PLHIV respectively [11]. Epi Info version 3.5 was used to calculate the required sample size [14]. Accordingly, the calculated sample size was 488 (244 for ART and pre-ART); after adding 10% contingency the sample was 536. Eligible study participants were identified by data collectors from the list of PLHIV who were on HIV care or on ART follow up from ART clinics of Debre Markos hospital and health center. Eligible PLHIV who were on pre-ART and ART history were given separate codes and then selected by simple random sampling using random number table. Moreover, in order to reduce falsely survival increment, study participants were asked by data collectors about treatment history for OIs.

Data collection instrument and procedure
Data abstraction format was developed from federal ministry of health HIV care/ART follow up form which is used in the ART clinic and also the patients' card; the format includes the following check list: The data were collected by reviewing HIV care/ART follow up form, laboratory requests and patients' card. If PLHIV develop any OI before completing treatment of any preceding OI while the patient is on study, the time of treatment, which is nearest to, end of the study was used as the starting time for study. If laboratory results (CD4 count, Hgb) were not found during OI treatment, the most recent laboratory results before treatment of OI were used as base line predictors. Length of follow up for each study participant was varied because of different enrollment time.
Reoccurrence of any OI was confirmed by reviewing HIV care/ ART follow-up form or patient card or by asking study participant during data collection period about treatment history for OIs out of the follow up health institution. The health status was assured by asking the study participants when she or he came to ART clinic for follow up, asking using registered address on follow up form like phone number, kebele, house number, or adherence supporter groups were used to get their homes and used to trace study participants.
Individuals who change from unexposed to exposed, drop-out/loss to follow-up/transferred out/dead by any disease other than OI where cause of death not confirmed during study period or not develop any OI at the end of the study period were censored. The outcome of each subject was dichotomized into censored or recurrence of any OI.
Three data collectors and one supervisor who had direct experience and working on ART clinic were recruited for data collection and supervision respectively. Data collectors and supervisor were trained on objectives of the study, selection of exposed and unexposed, confidentiality of information, the contents of the questionnaire and data quality management by the principal investigators.

Data quality management, processing and analysis
To maintain data quality, incompletely recorded follow up formats were excluded from abstraction to check the reliability and consistency of data and accordingly correction was made. Data cleaning and editing were made before analysis.
Each abstraction format was given a code and was entered in to Epi Info version 3.35 statistical software and exported to SPSS 16 and STATA 11 statistical packages for analysis of statistical inferences.
The patient cohort characteristics including age, CD4 count, Hgb value, time to reoccurrence of any OIs and body mass index (BMI) were described in terms of mean or median value and other characteristics like sex, residence, marital status, occupational status, educational status, WHO clinical staging, ART adherence, line of ART regimen, prophylaxis treatment and its adherence, functional status, final outcome of study (censored or reoccurrence of any OIs) were described in terms percentages, tables and graphs.
Proportion and incidence of any OI were calculated at the end of the study. Incidence rate was calculated by dividing total events to personweeks. The actuarial life table and Kaplan Meier survival was used to estimate survival time and log rank test was used for categorical variables to compare survival curves across each strata. Before running the Cox regression model assumption of proportional-hazard was checked by Schoenfeld residual with p-value > 0.1 (α=10%) and the assumption was not violated. Multi-colinearity was checked using Pearson correlation, tolerance or variance inflation factor and we found that base line ART regimen was highly correlated with follow up ART regimen (r=0.809 , p<0.0001) so that further analysis in the final model were not done for base line ART regimen. Similarly, follow up Hgb value were excluded in final model because of its correlation with base line Hgb value (r=0.598, p<0.0001) and it was done in only 10.8% of study participants. Exclusion of redundant variables was done to stabilize final model and to improve precision of estimation. Cox proportional-hazard model was used to calculate the univariate and multivariable adjusted hazard rate and to determine independent predictors of survival. In Multivariable cox proportional hazard model, only those variables which were associated with time to recurrence of any OI with p-value ≤ 0.2 in univariate analysis and not collinear were entered to the final model.

Definitions
Pre-ART PLHIV: The person whose HIV positive status confirmed but not eligible for ART; ART PLHIV: The person whose HIV positive status confirmed and started ART; Survival: The person without any OI recurrence; Censored: Non-recurrence of any OI in study participant during follow up on study but not sure for future recurrence;

Reoccurrence:
The happening or diagnosis of any OI by health personnel working in ART health center. Confidentiality and anonymity was maintained. Informed consent was clinic after completing the preceding treatment of any OI; Drop out: If a PLHIV on HIV care lost to follow up for more than three months as recorded by ART clinic personnel; Lost to follow up: If PLHIV on HIV care not seen for equal to or more than one month as recorded by ART clinic personnel;

Ethical consideration
Ethical approval and clearance were obtained from research and ethical committee of School of Public Health of Addis Ababa University. Permission was also obtained from the concerned bodies of the hospital and obtained from study participants to get permission to extract data from their medical records. To get study participants who were not coming to the ART clinic for follow up during data collection period, in addition of using already registered address like phone number, kebele, house number on follow up form and ART adherence supporter groups  With regard to functional status, more than three quarters of the participants were working both at base line (418, 78%) and at follow up (471, 87.1%).
More than four-fifth of the study participants were taking prophylaxis both at base line (443, 82.6%) and at follow up (453, 84.5%) and almost all of them had good drug adherence status both at base line (415, 93.7%) and at follow up (422, 93.2%).
Almost all of the participants (423, 95.5%) were taking Cotrimoxazole prophylaxis both at base line and at follow up (439, 96.7%).
Half of the study participants (268, 50%) were taking ART both at base line and at follow up. All participants were on first line ART regimens in which about one third were taking TDF+3TC+EFV regimen both at base line (101, 37.7%) and at follow up (106, 39.6%). Almost all study participants had good antiretroviral drug adherence both at base line (252, 94%) and follow up (253, 94.4%) ( Table 3).
were used to trace them. For study participants who were severely ill, with coma or having hearing impairment or died before data collection period while included in the study period, the nearest relatives (family) or legal representatives were asked to give permission to extract on medical records.

Results
In this historical cohort study, between 25 th March 2007 and 24 th March 2013, 8,974 PLHIV aged 18 years and above were evaluated ( Figure 1). Five hundred thirty six PLHIV who were on pre-ART and ART with 1:1 ratio each consisting 268 were followed for a total of 30971 person weeks and median of 43 person weeks. The minimum and maximum person week follow up was 2 and 258 respectively. The study assessed time to recurrence of any OI in pre-ART and ART PLHIV, its magnitude and baseline and follow up predictors of time to recurrence in PLHIV.

Clinical, laboratory and treatment information
At base line, three quarter of the study participants (400, 74.6%) had
In chi-square test, the proportion of recurrence was not statistically significant different in the overall or each type of OI in Pre-ART and ART PLHIV.
The overall incidence rate of any OI recurrence was 1.31 per 100 person weeks and it was 1.57 and 1.13 per 100 person weeks in pre-ART and ART PLHIV respectively. In the study area, frequently recurred OIs were recurrent upper respiratory tract infection 73 (13.6%), chronic diarrhea 52 (9.7%), pneumonia 46 (8.5%), oral candidiasis 43 (8%), herpes zoster 38 (7.1%) though their proportions and the commonly recurred OIs were different in pre-ART and ART PLHIV (Table 1).

Survival analysis
A total of 536 PLHIV were followed for a median of 43 (IQR=20. .75) person weeks. The minimum, maximum and total person weeks follow up was 2, 258 and 30971 respectively. According to the Kaplanmeier survival estimation, the median time of survival was 57 weeks (95%CI: 51.66-62.34). The actuarial life table analysis showed that most (63, 11.8%) OIs recurred from 10-20 weeks. The cumulative proportion of free from any OI recurrence up to week 20 was 81%. The cumulative proportion of free from any OI recurrence up to week 250 was 1% (   The median time of survival was different in pre-ART and ART PLHIV, that was 52 (95%CI: 45.24-58.76) and 64 (95% CI: 54.87-73.13) weeks respectively (Figures 2 and 3).  (Table 3).
In Multivariable cox proportional hazard model, only those variables which were associated with survival with p-value ≤ 0.2 and not collinear were entered to the final model. After adjustment for covariates, significant predictors reducing survival (risks for recurrence) were being widowed than married by 2.18 times, fair follow up prophylaxis adherence than good adherence by 7.27 times, fair base line ART adherence than good adherence by 14.83 times. The significant predictors that improve survival (prevent recurrence) were divorced than married by 0.57 times, compared to farmer being merchant, employed and student by 0.30, 0.22 and 0.15 times respectively, having base line Hgb value of ≥ g/dl than <10 by 0.42 times, compared ≤ 100 cells/μl CD4 count having 351-499 and ≥ 500 follow up CD4 count by 0.39 and 0.32 times respectively; moreover, taking prophylaxis at baseline, at follow up and taking ART by 0.55 and 0.49 by 0.522 times respectively. After adjusting for other variables, when follow up CD4 count increased by 50 cells/μl survival also increased by 0.91 times (p<0.0001), and when base line Hgb value increased by 5 g/dl survival also increased by 0.66 times (p=0.004) ( Table 4).

Discussion
In this historical cohort study, more than three quarter of the participants had recurrence of OIs. Proportion of recurrence was not significantly different (p=0.614) between Pre-ART and ART PLHIV. The proportion of OI recurrence in pre-ART PLHIV was slightly lower than the study in Northwest Ethiopia in which 82.4% patients present with any type of OIs at start of ART [15] and in other study in Felegehiot hospital among pre-ART HIV patients, it was 88. ART enrolment [9]. The smaller in magnitude was due to inclusion of all Pre-ART PLHIV who were on chronic HIV care and treated for any OIs but the previous studies [9,15] assessed only Pre-ART PLHIV who were enrolled for ART which might increase the magnitude because ART enrollment was done using WHO clinical staging and CD4 count.
This study showed taking ART reduces time to any OI recurrence which is supported by different studies [12,13,[16][17][18][19]. The one year follow-up study after ART initiation in Northwest Ethiopia showed ART reduces any OIs occurrence by 91.9%. HAART reduces the incidence of severe OIs by 21% during the first 6 months and 28% during subsequent follow up after adjusting for CD4 count [19].   [9,20]. This study revealed that base line fair ART adherence compared to good adherence was hazard for survival illustrating adherence is crucial to improving survival besides taking ART.

Antiretroviral treatment adherence is one of the challenges in the
This study revealed that survival was enhanced by taking prophylaxis at baseline and at follow up similar with other studies [21][22][23][24]. A critical appraisal in 2011 showed primary prophylaxis with Trimethoprim-sulfamethoxazole is preventing life-threatening OIs like PCP, toxoplasmosis and bacterial infections [21]. Primary prophylaxis with anti-tuberculosis regimens seems more effective at reducing the incidence of active tuberculosis in PLHIV [22]. An experimental study in Ugandan adults with Cotrimoxazole prophylaxis showed its effect on prevention of OIs like diarrhea in PLHIV. Compared to those remaining on cotrimoxazole, patients who discontinued had a relative risk of diarrhea of 1.8 and at least 1 episode of diarrhea occurred in 14% among those continued versus 25% in those discontinued. Participants who discontinued cotrimoxazole were more likely to be diagnosed with a respiratory tract infection [23]. Another study also showed Cotrimoxazole is preventing PCP (RR=0.59, p=0 .03) [24].
This study revealed having higher follow up CD4 count prolongs survival, compared ≤ 100 cells/μl; this result is in conformity with previous studies [13,18,19,25,26]. Similar cohort study also showed the risk of toxoplasmic encephalitis occurrence was increased by 30% for each 50-cell decrease in CD4+ cell count, independent of antiretroviral [13].

Conclusions
Since the introduction of free ART, more patients have been presented to HIV care and support. A number of PLHIV seeking HIV care are increasing through time in health institutions of Debre Markos to get the services. During a median of 43 person weeks follow up OIs were recurred in three quarter study participants (75.7%). The overall incidence rate of any OI recurrence was 1.31 per 100 person weeks. Independent significant predictors that reduce recurrence (risk factors) and improve (preventive factors) survival were identified. Those risk factors were being widowed than married, non-adherence of ART and prophylaxis treatments; however, preventive factors were being divorced compared to married, having occupational status of merchant, employed and student compared to farmer, having ≥10 g/dl Hgb value, having CD4 count 351 cells/μl and above compared to ≤100 cells/μl, taking ART and prophylaxis treatments.

Recommendations To hospitals and health centers with ART clinic (giving HIV care and support)
 PLHIV should be encouraged to take ART and prophylaxis drugs and counseled to adhere on them properly  Increasing the CD4 count and Hgb value, using nutrition and drug treatments are crucial to improve survival  Preventive efforts should focus on high risk groups such as widowed, not adhering ART or prophylaxis  The ART care should be further enhanced to improve survival.

To Debre Markos town health office and other responsible organizations
 In-service training should be given for the healthcare provider on HIV/AIDS care and support especially on how to distinguish and manage patients with high risk  Health professionals should be encouraged to properly document patients' healthcare data  Priority should be given for increasing job opportunities for PLHIV in governmental or non-governmental organizations or facilitate conditions to join other options.

To research and academic institutions
 Further studies for estimating economic losses for subsequent recurrence of OI is recommended  Further observational studies with prospective design to ascertain the findings are recommended.