Adherence with Injectibal Prophylaxis for Venous Thromboembolism (VTE) Following Total Hip (THR) and Total Knee (TKR) Replacement Surgery: Complete Registry.

Patients undergoing major hip or knee arthroplasty are at high risk of venous thromboembolism (VTE). Guidelines recommend continuation of anticoagulant thromboprophylaxis for up to 35 days after hip and knee arthroplasty but little is known about adherence to injectable VTE prophylaxis.

1) To describe adherence with injectable VTE prophylaxis following elective THR and TKR surgery 2) To analyze the factors impacting patient adherence.

A prospective cohort study was conducted in 8 orthopaedic Canadian centres. Patients undergoing THR or TKR were enrolled at the time of discharge from the acute care ward. Patients prescribed with injectable prophylaxis at discharge from acute care ward / rehabilitation unit were contacted by phone within 6 weeks of discharge to collect data on their use of the prophylaxis. Overall Adherence (OA) was calculated as the weighted average of the adherence rate in the acute care ward/rehabilitation unit (inpatient) and the adherence rate for the follow-up phase (out patient). The inpatient adherence was based on records and the percent was calculated as doses administered divided by doses prescribed × 100. The outpatient adherence defines as adherence post discharge from the acute care ward/rehabilitation unit and was based on the results of the follow up call and the percent was calculated as number of syringes dispensed minus number of unused syringes left / total number of syringes that should have been injected out of the hospital as of the day of call × 100.

Of the 239 patients screened, 234 patients were enrolled. 198 were discharged directly home with a prescription for injectable prophylaxis and 36 patients went to a rehabilitation unit of whom 15 patients completed their injectable prophylaxis at the rehabilitation unit and 21 were subsequently discharged home with a prescription for injectable prophylaxis. Of the total 219 patients discharged home 9 (4.1%) were not reachable for the follow-up call. The inpatient adherence data were availabel for all 234 enrolled patients whereas outpatient adherence data were availabel for 210 patients. The calculated OA data for 225 patients represents the adherence of all enrolled patient who completed their injectable prophylaxis in the rehabilitation unit or discharged home and reachable for the follow-up call.

Median duration of VTE prophylaxis at the follow-up phase was 10 days ranging from 1 to 45 days with 75% of the patients having duration of more than 1 week.

The mean (±sd) age was 65.5 years (11.1) ranging from 23 to 91, 39.3% were males, 35.9% underwent total hip replacement.

The median and interquartile range (IQ) for overall adherence was 96.6% (92.9-100.0), for inpatient adherence was 100.0% (100.0-100.0) and for outpatient adherence was 94.9% (88.9-100.0). The range of OA was from 16.7% to 180.0%. OA adherence below 80% in 6 (2.7%) patients was associated with cost of drugs (1), forgot (2), reason not specified (3). OA above 120% in 3 (1.3%) patients was associated with injecting extra syringes dispensed.

The Complete Registry is the first Canadian registry that provides key real life data on adherence with injectable VTE prophylaxis and the factors impacting the adherence. Median inpatient and outpatient adherence was over 90% with few instances of under and over adherence.

Semchuk:Pfizer Canada: Honoraria; Boehringer Ingelheim: Honoraria; Sanofi Aventis: Consultancy, Honoraria, Research Funding. Backstein:SanofiAventis: Honoraria. Stewart:Sanofi-Aventis Canada: Employment. Eikelboom:sanofi-aventis: Consultancy, Honoraria, Research Funding; Portola: Consultancy, Honoraria; GSK: Consultancy, Honoraria, Research Funding; BI: Consultancy, Honoraria; Bayer: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria.