Organizational boundaries of medical practice: the case of physician ownership of ancillary services

Physician ownership of in-office ancillary services (IOASs) has come under increasing scrutiny. Advocates of argue that IOASs allow physicians to supervise the quality and coordination of care. Critics have argued that IOASs create financial incentives for physicians to increase ancillary service volume. In this paper we develop a conceptual framework to evaluate the tradeoffs associated with physician ownership of IOASs. There is some evidence supporting the existence of scope and transaction economies in IOASs. Improvement in flow and continuity of care are likely to generate scope economies and improvements in quality monitoring and reductions in consumer transaction costs are likely to generate transaction economies. Other factors include the capture of upstream and downstream profits, but these incentives are likely to be small compared to scope and transaction economies. Policy debates on the merits of IOASs should include an explicit assessment of these tradeoffs. This research was supported in part by funding from the American Association of Orthopaedic Surgeons (AAOS)

Economic evaluation of procalcitonin-guided antibiotic therapy in acute respiratory infections: a US health system perspective

Background: Whether or not antibiotic stewardship protocols based on procalcitonin levels results in cost savings remains unclear. Herein, our objective was to assess the economic impact of adopting procalcitonin testing among patients with suspected acute respiratory tract infection (ARI) from the perspective of a typical US integrated delivery network (IDN) with a 1,000,000 member catchment area or enrollment. Methods: To conduct an economic evaluation of procalcitonin testing versus usual care we built a cost-impact model based on patient-level meta-analysis data of randomized trials. The meta-analytic data was adapted to the US setting by applying the meta-analytic results to US lengths of stay, costs, and practice patterns. We estimated the annual ARI visit rate for the one million member cohort, by setting (inpatient, ICU, outpatient) and ARI diagnosis. Results: In the inpatient setting, the costs of procalcitonin-guided compared to usual care for the one million member cohort was $2,083,545, compared to$2,780,322, resulting in net savings of nearly $700,000 to the IDN for 2014. In the ICU and outpatient settings, savings were$73,326 and $5,329,824, respectively, summing up to overall net savings of$6,099,927 for the cohort. Results were robust for all ARI diagnoses. For the whole US insured population, procalcitonin-guided care would result in $1.6 billion in savings annually. Conclusions: Our results show substantial savings associated with procalcitonin protocols of ARI across common US treatment settings mainly by direct reduction in unnecessary antibiotic utilization. These results are robust to changes in key parameters, and the savings can be achieved without any negative impact on treatment outcomes

Distribution and abundance of the invasive seagrass Halophila stipulacea and associated benthic macrofauna in Carriacou, Grenadines, Eastern Caribbean

Embargo until 12 Oct 2019.The invasive seagrass Halophila stipulacea has spread throughout the eastern Caribbean since it was first recorded in Grenada in 2002. We quantified the distribution and abundance of H. stipulacea, and its associated macroinvertebrate fauna, in sampling stations and transects around the island of Carriacou (a nearby dependency of Grenada) in early 2016. Halophila stipulacea occurred in extensive monospecific stands (average bottom cover, 62%), or smaller mixed stands with native seagrass (Thalassia testudinum, Syringodium filiforme, Halodule wrightii), at 1–5 m depth in large bays along the leeward (west) coast. It was sparsely distributed on the more wave-exposed east and south coasts, usually in mixed patches with native seagrass. In leeward bays, H. stipulacea has largely replaced the native seagrass H. wrightii, providing a novel biogenic habitat for various filter-feeding invertebrates living within the turf-like leaf canopy (e.g., sponges, ascidians, bivalves, ophiuroids), and sea urchins (mainly Tripneustes ventricousus) and a microphagous sea star (Oreaster reticulatus) that graze upon it. Populations of the sea star consisted mainly of juveniles indicating the seagrass may serve as a nursery habitat for this endangered species. The spread of H. stipulacea along the leeward coast of Carriacou in recent years represents a community-level shift in the shallow subtidal zone, with attendant changes in habitat structure, species composition, and trophic interactions.acceptedVersio

Disease as a Control of Sea Urchin Populations in Nova Scotian Kelp Beds

In Nova Scotia, Canada, periodic outbreaks of amoebic disease (paramoebiasis) cause mass mortality of sea urchins Strongylocentrotus droebachiensis in subtidal barrens. However, in kelp beds, where sea urchins are cryptic and generally less dense than in barrens, disease outbreaks are not readily observed and the importance of disease in regulating these populations is unknown. To determine whether sea urchin populations in kelp beds are controlled by disease, we analyzed population data from kelp beds at a single location (St. Margarets Bay) across a span of 44 yr (1968 to 2012) to compare changes in size structure and density in relation to the timing of disease outbreaks in adjacent sea urchin aggregations and barrens. We found that sea urchin density, maximum test diameter and percentage of adults decreased following disease outbreaks and increased during intervening periods without disease, indicating that disease regulates the population in kelp beds by limiting survival to adulthood. Our results suggest that disease has replaced predation as a major agent controlling sea urchin populations in Nova Scotian kelp beds

Effects of Sea Urchin Disease on Coastal Marine Ecosystems

Outbreaks of disease in herbivorous sea urchins have led to ecosystem phase shifts from urchin barrens to kelp beds (forests) on temperate rocky reefs, and from coral to macroalgal-dominated reefs in the tropics. We analyzed temporal patterns in epizootics that cause mass mortality of sea urchins, and consequent phase shifts, based on published records over a 42-year period (1970-2012). We found no evidence for a general increase in disease outbreaks among seven species of ecologically important and intensively studied sea urchins. Periodic waves of recurrent amoebic disease of Strongylocentrotus droebachiensis in Nova Scotia coincide with periods when the system was in a barrens state and appear to have increased in frequency. In contrast, following a major epizootic that decimated Diadema antillarum throughout the Caribbean in 1983, subsequent outbreaks of disease were highly localized and none have been reported since 1991. Epizootics of Strongylocentrotus in the NW Atlantic and NE Pacific, and Paracentrotus and Diadema in the eastern Atlantic, have been linked to climate change and overfishing of sea urchin predators. The spatial extent of recurrent disease outbreaks in these species, and the frequency of phase shifts associated with these epizootics, has decreased over time due to the expansion of the macroalgal state and its stabilization through positive feedback mechanisms. Longitudinal studies to monitor disease outbreaks in sea urchin populations and improved techniques to identify causative agents are needed to assess changes in the frequency and extent of epizootics, which can profoundly affect the structure and functioning of coastal marine ecosystems

Data from: Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds

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Data from: Detrital subsidy from subtidal kelp beds is altered by the invasive green alga Codium fragile ssp. fragile

Invasive species have the potential to alter the dynamics of detrital subsidy from high to low productivity areas through changes in quantity and nutritional quality of detrital material. We examined the effect of the invasive alga Codium fragile ssp. fragile on the nature of detrital export from subtidal algal beds off Nova Scotia, Canada, by comparing changes in mass, nutritional quality (%C, %N, C/N ratio), concentration of dimethylsulfoniopropionate (DMSP, a secondary metabolite that deters grazers), and isotopic composition (δ13C and δ15N) between C. fragile and the native kelp Saccharina latissima at 4 wk intervals over 16 wk of degradation in cages on a sand bottom at 19 m depth. C. fragile degraded more slowly, and had a consistently lower C/N and higher DMSP concentration, than S. latissima. Isotope signatures did not differ between algal species: δ15N became slightly enriched (~1‰) after 16 wk of degradation, with no change in δ13C. We also compared macrofaunal communities associated with degrading thalli of each algal species and found significantly higher abundances of invertebrates (mainly capitellid polychaetes) on S. latissima after 8 wk of degradation, resulting in lower evenness (J’) and diversity (H’) on S. latissima compared to C. fragile. Macrofaunal community composition became similar between algal species at 12 and 16 wk in concordance with decreases in C/N ratio in S. latissima and DMSP concentration in C. fragile. Our results indicate that differences in biochemical composition and the rate of degradation between C. fragile and native kelps result in community-level effects in areas linked to shallow algal beds via the transfer of detritus

Data from: Detrital subsidy from subtidal kelp beds is altered by the invasive green alga Codium fragile ssp. fragile

Invasive species have the potential to alter the dynamics of detrital subsidy from high to low productivity areas through changes in quantity and nutritional quality of detrital material. We examined the effect of the invasive alga Codium fragile ssp. fragile on the nature of detrital export from subtidal algal beds off Nova Scotia, Canada, by comparing changes in mass, nutritional quality (%C, %N, C/N ratio), concentration of dimethylsulfoniopropionate (DMSP, a secondary metabolite that deters grazers), and isotopic composition (δ13C and δ15N) between C. fragile and the native kelp Saccharina latissima at 4 wk intervals over 16 wk of degradation in cages on a sand bottom at 19 m depth. C. fragile degraded more slowly, and had a consistently lower C/N and higher DMSP concentration, than S. latissima. Isotope signatures did not differ between algal species: δ15N became slightly enriched (~1‰) after 16 wk of degradation, with no change in δ13C. We also compared macrofaunal communities associated with degrading thalli of each algal species and found significantly higher abundances of invertebrates (mainly capitellid polychaetes) on S. latissima after 8 wk of degradation, resulting in lower evenness (J’) and diversity (H’) on S. latissima compared to C. fragile. Macrofaunal community composition became similar between algal species at 12 and 16 wk in concordance with decreases in C/N ratio in S. latissima and DMSP concentration in C. fragile. Our results indicate that differences in biochemical composition and the rate of degradation between C. fragile and native kelps result in community-level effects in areas linked to shallow algal beds via the transfer of detritus

Data from: Spatial and temporal variation in grazing damage by the gastropod Lacuna vincta in Nova Scotian kelp beds

Population increases of the gastropod Lacuna vincta have been associated with significant damage to kelp blades and decreases in kelp biomass in subtidal kelp beds off Nova Scotia, Canada. We measured the total level and along-blade distribution of grazing damage by Lacuna vincta on the dominant kelp species at 5 sites in Nova Scotia, Canada, over a 15 mo period. Grazing was typically low or absent in the basal regions of blades, consistent with seasonal fluctuations in growth and physical properties of blade tissues. Grazing was largely concentrated in middle and distal sections, although this distribution varied with site exposure and over time. The cover of the invasive bryozoan Membranipora membranacea on the surface of kelp blades did not have a strong effect on grazing by L. vincta. The total level of grazing damage (max. 1% of blade area for Saccharina longicruris and 1.5% for Laminaria digitata) varied seasonally, with peaks in September at some sites. Spatial variation was driven in part by a negative relationship with site exposure. In a field experiment, simulated grazing damage that exceeded a threshold value of 0.5 to 1.0% of blade area caused a significant increase in blade loss during a period of heavy wave action due to a passing hurricane. Our results show that direct reductions in kelp biomass through grazing by L. vincta are relatively small, but can indirectly lead to significant losses of kelp biomass during large wave events