Modelling multi-site transmission of the human papillomavirus and its impact on vaccination effectiveness.

OBJECTIVE: Previous HPV models have only included genital transmission, when evidence suggests that transmission between several anatomical sites occurs. We compared model predictions of population-level HPV vaccination effectiveness against genital HPV16 infection in women, using a 1) uni-site (genital site), and a 2) multi-site model (genital and one extragenital site). METHODS: We developed a uni-site and a multi-site deterministic HPV transmission model, assuming natural immunity was either site-specific or systemic. Both models were calibrated to genital HPV16 prevalence (5%-7.5%), whilst the multi-site model was calibrated to HPV16 prevalence representative of oral (0%-1%) and anal (1%-7.5%) sites. For each model, we identified 2500 parameter sets that fit endemic genital and extragenital prevalences within pre-specified target ranges. In the Base-case analysis, vaccination was girls-only with 40% coverage. Vaccine efficacy was 100% for all sites with lifetime protection. The outcome was the relative reduction in genital HPV16 prevalence among women at post-vaccination equilibrium (RRprev). RRprev was stratified by extragenital prevalence pre-vaccination. RESULTS: Under assumptions of site-specific immunity, RRprev with the multi-site model was generally greater than with the uni-site model. Differences between the uni-site and multi-site models were greater when transmission from the extragenital site to the genital site was high. Under assumptions of systemic immunity, the multi-site and uni-site models yielded similar RRprev in the scenario without immunity after extragenital infection. In the scenario with systemic immunity after extragenital infection, the multi-site model yielded lower predictions of RRprev than the uni-site model. CONCLUSIONS: Modelling genital-site only transmission may overestimate vaccination impact if extragenital infections contribute to systemic natural immunity or underestimate vaccination impact if a high proportion of genital infections originate from extragenital infections. Under current understanding of heterosexual HPV transmission and immunity, a substantial bias from using uni-site models in predicting vaccination effectiveness against genital HPV infection is unlikely to occur.

Secondary impairments after spinal cord injury: a population-based study.

OBJECTIVE: To determine the prevalence of secondary impairments among individuals with long-standing spinal cord injury in Quebec and the potential relationships between these impairments and several variables. DESIGN: A review of 2,200 medical files was conducted to determine the target population; 976 patients were selected randomly and mailed questionnaires. The results were based on 482 individuals with spinal cord injury who returned the completed questionnaire. The questionnaire included 14 subsections, such as sociodemographic, medical, psychosocial, and environmental information. The medical section, including the type and level of lesion and the presence of secondary impairments, was analyzed. RESULTS: Urinary tract infection, spasticity, and hypotension were the most frequently reported secondary impairments, regardless of the severity of injury. Relationships between the prevalence of secondary impairments and the duration of injury, as well as perceived health status, were observed. CONCLUSIONS: This is the first study to describe secondary impairments after long-standing spinal cord injury in Quebec. Patients with spinal cord injury still present a high prevalence of secondary impairments many years after their rehabilitation, despite preventive education or medical follow-up visits. Further studies are required to determine the specific impact that these impairments have on the patients' social role and their quality-of-life.

Decision analysis modelling of costs and outcomes following cefepime monotherapy in Canada.

OBJECTIVE: To evaluate the comparative cost of treatment and intermediate outcomes (percentage resistant organisms, days in hospital, etc) among cefepime and alternative parenteral antibiotics used for empiric monotherapy. DESIGN: Decision analysis model, based on published literature, clinical trial results and information from infectious disease clinicians. SETTING: A Canadian tertiary care hospital. INTERVENTION: Comparison of cefepime, ceftazidime, ceftriaxone, cefotaxime and ciprofloxacin in the treatment of lower respiratory tract infections, urinary tract infections, skin/soft tissue infections, septicemia and febrile neutropenia. MAIN RESULTS: Cefepime treatment results in the lowest average cost per patient when used as initial empiric therapy for lower respiratory tract infections and for skin/soft tissue infections. Cefepime therapy is among the lowest cost treatments for the other infectious disease conditions and has the lowest cost for a weighted 'average' condition. Sensitivity analysis indicates that model results are most sensitive to duration of hospitalization. CONCLUSIONS: Initial empiric monotherapy with cefepime for serious infectious disease conditions may result in cost savings compared with alternative parenteral agents.