The Southern Alberta Clinic Cohort (SAC) includes all HIV-infected patients receiving HIV care and living within southern Alberta, Canada. Patients are automatically included in the cohort when they initiate HIV care within a centralised outpatient program. SAC provides exclusive, comprehensive interdisciplinary care to all HIV patients living in southern Alberta including pharmaceuticals, outpatients, and laboratory tests. All individuals testing positive for HIV are referred to SAC located in Calgary, Alberta. Over 90% of patients reside within the immediate Calgary region. Inpatient services are provided in one of 3 local hospitals.
Administrative data including demographic, clinical characteristics as well as the direct cost of care are collected on all individuals on a routine basis during every clinical contact. Use of this administrative data was approved by the University Conjoint Medical committee on medical bioethics.
We include all newly infected HIV individuals diagnosed within the region who accessed their initial HIV treatment at SAC (“locally diagnosed patients”). Individuals who were diagnosed elsewhere were included if they were initiated care within 6 months of their diagnosis and had not accessed HIV elsewhere prior to their 1st SAC visit. We include all individuals initiating care between 1 Jan 1995 and 1 Jan 2010. To be included, patients must have had at least one regular clinic visit. Patients were followed until they moved, were lost to followed, died or until 1 April 2010.
We use the definition of “late presenters” as those patients who initiated care with a CD4 count <350/mm3 although we also subdivide this group by CD4 count > or < than 200/mm3 for comparisons with earlier uses of the term “late presenters.” We collected the patient's gender, age at clinic visit, risk factor (MSM, MSW, IVDU, other) and self-reported ethnicity (Caucasian/non-Caucasian) at the initial visit. We recorded the patient's initial CD4 count taken within 30 days of the initial visit and any recorded AIDS defining condition at diagnosis.
The Southern Alberta Clinic Cohort has been continuously tracking the direct cost of care for all HIV-infected patients followed at the regionalized Southern Alberta Clinic. SAC established a “costing search engine” that routinely captures all the direct costs of care including ARV (antiretroviral) and non-ARV drug costs, all outpatient clinic visits including laboratory texts and referrals to non-HIV specialists, and the cost of inpatient (i.e., hospitalizations) visits for both HIV and non-HIV-related admissions. Costs are collected per patient, per demographic population, or per a number of other variables including the CD4 status of the individual patient.
For this study, the direct costs of care were collected between 1/1/1995 and 12/31/2009. Costs were collected from the original costing source or agency using a methodology previously described [16
]. Briefly, we collected the direct costs of drugs (antiretroviral (ARV) and nonantiretroviral drugs), outpatient clinical care (including physician and laboratory costs), and inpatient (hospital) care. ARV and non-ARV drug costs, lab utilization, and outpatient care costs were derived directly from the SAC pharmacy, Calgary Laboratory Services, and the SAC-costing database whereas inpatient costs (i.e., unit service costs) were supplied by the regional health service providers. The unit costs used are market values charged to the regional payer (Alberta Health Services). All costs were obtained directly from the costing agencies and reported in Canadian dollars adjusted for inflation to 2009.
Annual costs for patients who initiate HIV care at SAC are reported from the date of initiating year to December 31st of that particular year. Costs are then adjusted as mean cost per patient per month (PPPM) in 2009 Cdn$ over the time followed in that year, and cumulatively for patients initiating care ±350/mm3. The annual cost for “late presenters” is reported as a proportion of all costs for newly diagnosed HIV patients accessing care for the first time. Long-term or “lifetime” costs are determined from the date of initiating HIV care to the date they moved, were LTFU (lost to followup), died, or 4/1/2010 and, are reported as mean PPPM or PPPY (per patient per year) costs.
Health care utilization data is based on number of clinic visits, laboratory tests, visits to HIV, and non-HIV physicians (i.e., outpatient visits), and the number of hospital admissions (inpatient visits/length of stay (LOS)). Administrative data were obtained directly from the SAC database and hospitalization admission records. Visits for physicians for non-HIV related conditions were self reported by the patients and may be underreported. Clinical protocols on recommended frequency of clinic visits, ART options, and laboratory testing algorithms for patients remained stable during the study period.
We compare the PPPM cost of care for late presenters initiating care at SAC to that of early presenters over the same time period and under the same clinical protocols. We provide descriptive statistics (i.e., mean, standard deviations, medians) to describe the data. We use Student t-tests for normally distributed data and Mann Whitney U-test for non normally distributed variables to compare the populations. Chi-square tests were used to compare proportions. P < .05 was set for the level of significance.