Factors associated with the frequency of monitoring of liver enzymes, renal function and lipid laboratory markers among individuals initiating combination antiretroviral therapy: a cohort study.
BACKGROUND
As the average age of the HIV-positive population increases, there is increasing need to monitor patients for the development of comorbidities as well as for drug toxicities.


METHODS
We examined factors associated with the frequency of measurement of liver enzymes, renal function tests, and lipid levels among participants of the Canadian Observational Cohort (CANOC) collaboration which follows people who initiated HIV antiretroviral therapy in 2000 or later. We used zero-inflated negative binomial regression models to examine the associations of demographic and clinical characteristics with the rates of measurement during follow-up. Generalized estimating equations with a logit link were used to examine factors associated with gaps of 12 months or more between measurements.


RESULTS
Electronic laboratory data were available for 3940 of 7718 CANOC participants. The median duration of electronic follow-up was 3.5 years. The median (interquartile) rates of tests per year were 2.76 (1.60, 3.73), 2.55 (1.44, 3.38) and 1.42 (0.50, 2.52) for liver, renal and lipid parameters, respectively. In multivariable zero-inflated negative binomial regression models, individuals infected through injection drug use (IDU) were significantly less likely to have any measurements. Among participants with at least one measurement, rates of measurement of liver, renal and lipid tests were significantly lower for younger individuals and Aboriginal Peoples. Hepatitis C co-infected individuals with a history of IDU had lower rates of measurement and were at greater risk of having 12 month gaps between measurements.


CONCLUSIONS
Hepatitis C co-infected participants infected through IDU were at increased risk of gaps in testing, despite publicly funded health care and increased risk of comorbid conditions. This should be taken into consideration in analyses examining factors associated with outcomes based on laboratory parameters.
Toronto General Research Institute, University Health Network, Toronto, Canada. jennifer.gillis@mail.utoronto.ca.|University of Toronto, Toronto, Canada. jennifer.gillis@mail.utoronto.ca.
Jennifer
J
Gillis
University of Toronto, Toronto, Canada. ahmed.bayoumi@utoronto.ca.|Centre for Research on Inner City Health, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada. ahmed.bayoumi@utoronto.ca.
Ahmed M
AM
Bayoumi
University of Toronto, Toronto, Canada. ann.burchell@utoronto.ca.|Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada. ann.burchell@utoronto.ca.|Department of Family and Community Medicine, St. Michael's Hospital, Toronto, Ontario, Canada. ann.burchell@utoronto.ca.
Ann N
AN
Burchell
University of Ottawa, The Ottawa Hospital Research Institute, Ottawa, Canada. ccooper@ottawahospital.on.ca.
Curtis
C
Cooper
McGill University Health Centre, McGill University, Montreal, Canada. marina.klein@mcgill.ca.
Marina B
MB
Klein
University of Toronto, Toronto, Canada. mona.loutfy@wchospital.ca.|Women's College Research Institute, Toronto, Canada. mona.loutfy@wchospital.ca.|Maple Leaf Medical Clinic, Toronto, Canada. mona.loutfy@wchospital.ca.
Mona
M
Loutfy
Clinique Médicale l'Actuel, Montreal, Canada. nima.machouf@lactuel.ca.
Nima
N
Machouf
British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada. jmontaner@cfenet.ubc.ca.
Julio Sg
JS
Montaner
McGill University Health Centre, McGill University, Montreal, Canada. chris.tsoukas@muhc.mcgill.ca.
Chris
C
Tsoukas
British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada. bobhogg@cfenet.ubc.ca.|Simon Fraser University, Burnaby, Canada. bobhogg@cfenet.ubc.ca.
Robert S
RS
Hogg
Toronto General Research Institute, University Health Network, Toronto, Canada. janet.raboud@uhnresearch.ca.|University of Toronto, Toronto, Canada. janet.raboud@uhnresearch.ca.
Janet
J
Raboud
D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D015415:Biomarkers / Q000032:analysis; D002170:Canada; D015331:Cohort Studies; D060085:Coinfection; D004798:Enzymes / Q000032:analysis*; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000188:drug therapy* / Q000378:metabolism; D006526:Hepatitis C / Q000150:complications; D006801:Humans; D007677:Kidney Function Tests; D008055:Lipids / Q000097:blood*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D015819:Substance Abuse, Intravenous / Q000150:complications
D015415:Biomarkers; D004798:Enzymes; D008055:Lipids