A review of the study designs and statistical methods used in the determination of predictors of all-cause mortality in HIV-infected cohorts: 2002-2011.
BACKGROUND
Research in the predictors of all-cause mortality in HIV-infected people has widely been reported in literature. Making an informed decision requires understanding the methods used.


OBJECTIVE
We present a review on study designs, statistical methods and their appropriateness in original articles reporting on predictors of all-cause mortality in HIV-infected people between January 2002 and December 2011. Statistical methods were compared between 2002-2006 and 2007-2011. Time-to-event analysis techniques were considered appropriate.


METHODS
Pubmed/Medline.


METHODS
Original English-language articles were abstracted. Letters to the editor, editorials, reviews, systematic reviews, meta-analysis, case reports and any other ineligible articles were excluded.


RESULTS
A total of 189 studies were identified (n = 91 in 2002-2006 and n = 98 in 2007-2011) out of which 130 (69%) were prospective and 56 (30%) were retrospective. One hundred and eighty-two (96%) studies described their sample using descriptive statistics while 32 (17%) made comparisons using t-tests. Kaplan-Meier methods for time-to-event analysis were commonly used in the earlier period (n = 69, 76% vs. n = 53, 54%, p = 0.002). Predictors of mortality in the two periods were commonly determined using Cox regression analysis (n = 67, 75% vs. n = 63, 64%, p = 0.12). Only 7 (4%) used advanced survival analysis methods of Cox regression analysis with frailty in which 6 (3%) were used in the later period. Thirty-two (17%) used logistic regression while 8 (4%) used other methods. There were significantly more articles from the first period using appropriate methods compared to the second (n = 80, 88% vs. n = 69, 70%, p-value = 0.003).


CONCLUSIONS
Descriptive statistics and survival analysis techniques remain the most common methods of analysis in publications on predictors of all-cause mortality in HIV-infected cohorts while prospective research designs are favoured. Sophisticated techniques of time-dependent Cox regression and Cox regression with frailty are scarce. This motivates for more training in the use of advanced time-to-event methods.
Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa ; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
Kennedy N
KN
Otwombe
Centre for Applied Biostatistics, Occupational and Environmental Medicine, University of Gothenburg, Gothenburg, Sweden.
Max
M
Petzold
Perinatal HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa ; Johns Hopkins University, Center for TB Research, Baltimore, Maryland, United States of America.
Neil
N
Martinson
School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
Tobias
T
Chirwa
D002423:Cause of Death; D015331:Cohort Studies; D015658:HIV Infections / Q000175:diagnosis* / Q000401:mortality*; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000706:statistics & numerical data*; D011379:Prognosis; D016016:Proportional Hazards Models; D012107:Research Design / Q000592:standards*