Economic Evaluations of Establishing Opioid Overdose Prevention Centers in 12 North American cities: A Systematic Review

OBJECTIVES

Overdose prevention centers (OPCs) provide a safe place where people can consume preobtained drugs under supervision so that a life-saving medical response can be provided quickly in the event of an overdose. OPCs are programs that are established in Canada and have recently become legally sanctioned in only a few United States jurisdictions.

METHODS

We conducted a systematic review that summarizes and identifies gaps of economic evidence on establishing OPCs in North America to guide future expansion of OPCs.

RESULTS

We included 16 final studies that were evaluated with the Consolidated Health Economic Evaluation Reporting Standards and Drummond checklists. Eight studies reported cost-effectiveness results (eg, cost per overdose avoided or cost per quality-adjusted life-year), with 6 also including cost-benefit; 5 reported only cost-benefit results, and 3 cost offsets. Health outcomes primarily included overdose mortality outcomes or HIV/hepatitis C virus infections averted. Most studies used mathematical modeling and projected OPC outcomes using the experience of a single facility in Vancouver, BC.

CONCLUSIONS

OPCs were found to be cost-saving or to have favorable cost-effectiveness or cost-benefit ratios across all studies. Future studies should incorporate the experience of OPCs established in various settings and use a greater diversity of modeling designs.

Src tyrosine kinase is a novel direct effector of G proteins

Heterotrimeric G proteins transduce signals from cell surface receptors to modulate the activity of cellular effectors. Src, the product of the first characterized proto-oncogene and the first identified protein tyrosine kinase, plays a critical role in the signal transduction of G protein-coupled receptors. However, the mechanism of biochemical regulation of Src by G proteins is not known. Here we demonstrate that Galphas and Galphai, but neither Galphaq, Galpha12 nor Gbetay, directly stimulate the kinase activity of downregulated c-Src. Galphas and Galphai similarly modulate Hck, another member of Src-family tyrosine kinases. Galphas and Galphai bind to the catalytic domain and change the conformation of Src, leading to increased accessibility of the active site to substrates. These data demonstrate that the Src family tyrosine kinases are direct effectors of G proteins.

Selection for retroviral insertions into regulated genes

Gene traps can be used to monitor faithfully the changes in gene expression accompanying several cellular processes. Here, we present a strategy that combines retroviral gene trap vectors, efficient selection schemes based on fluorescence-activated cell sorting or dominant positive and negative drug selection, and appropriately responsive cell lines in order to enrich for retroviral insertions into regulated genes (i.e., genes participating in cellular differentiation processes and genes induced by growth factors, drugs, or neurotransmitters, etc.). As an example, we applied this approach to the identification of insertions into genes activated by a MyoD protein, using a MyoD-responsive fibroblast line. In a single experiment designed to demonstrate the feasibility of this approach, we have been able to screen thousands of gene trap integrations and to select those that represent direct or indirect targets of MyoD. Distinct patterns of regulation were observed during myogenic determination. Sequences flanking the integrations can be rescued with several approaches, and they can be used to isolate the host genes or can serve as entry points for genome-wide sequencing projects.

Gene trapping in differentiating cell lines: regulation of the lysosomal protease cathepsin B in skeletal myoblast growth and fusion

To identify genes regulated during skeletal muscle differentiation, we have infected mouse C2C12 myoblasts with retroviral gene trap vectors, containing a promoterless marker gene with a 5' splice acceptor signal. Integration of the vector adjacent to an actively transcribed gene places the marker under the transcriptional control of the endogenous gene, while the adjacent vector sequences facilitate cloning. The vector insertionally mutates the trapped locus and may also form fusion proteins with the endogenous gene product. We have screened several hundred clones, each containing a trapping vector integrated into a different endogenous gene. In agreement with previous estimates based on hybridization kinetics, we find that a large proportion of all genes expressed in myoblasts are regulated during differentiation. Many of these genes undergo unique temporal patterns of activation or repression during cell growth and myotube formation, and some show specific patterns of subcellular localization. The first gene we have identified with this strategy is the lysosomal cysteine protease cathepsin B. Expression from the trapped allele is upregulated during early myoblast fusion and downregulated in myotubes. A direct role for cathepsin B in myoblast growth and fusion is suggested by the observation that the trapped cells deficient in cathepsin B activity have an unusual morphology and reduced survival in low-serum media and undergo differentiation with impaired cellular fusion. The phenotype is reproduced by antisense cathepsin B expression in parental C2C12 myoblasts. The cellular phenotype is similar to that observed in cultured myoblasts from patients with I cell disease, in which there is diminished accumulation of lysosomal enzymes. This suggests that a specific deficiency of cathepsin B could contribute to the myopathic component of this illness.

Absorption of gamma benzene hexachloride following application of Kwell shampoo

Serum concentrations of gamma benzene hexachloride were determined in 9 children following application of 1% GBH shampoo for treatment of pediculosis capitis. GBH was present in the blood of all patients 2-24 hours following application. Four patients, who were retreated because of the persistence of living lice, had GBH in their pretreatment blood specimens. GBH levels in these latter patients were larger after retreatment than after the initial application, indicating that there may have been accumulation of the drug.

Absorption of lindane (gamma benzene hexachloride) in infants and children

Concentrations of lindane (gamma benzene hexachloride) were measured in blood from children who had received treatment with 1% lindane lotion. Lindane was present in the blood of all patients from two of 48 hours following application. Concentrations were inversely related to weight, surface area, and were independent of the quantity of lindane applied.