The long-term impact of eGFR reporting on referral patterns.

BACKGROUND: The prognostic significance of CKD has driven the widespread introduction of automated estimated glomerular filtration rate (eGFR) reporting, and the incorporation of CKD in the revised Quality Outcomes Framework (QOF) of the General Medical Services (GMS) contract in the U.K. AIMS: To assess the long-term impact of the introduction of these two initiatives, on patient referral numbers to a nephrology service. METHODS: Data was collected on the numbers and basic characteristics of all new patients referred from April 2005 to March 2011, to one NHS Health Board. RESULTS: Introduction of eGFR reporting and CKD QOF domains was associated with a significant increase in the number of referrals, which was sustained. The initiatives also led to a sustained increase in the mean age of the patients at referral, predominantly due to an increase in the age of female patients referred. There was also an increase in the proportion of female patients referred. In the immediate aftermath of the introduction of change there was a transient decrease in the average eGFR at referral, a decrease in age of patients referred with an eGFR <15ml/min and an increase in the eGFR of patients >70yrs of age. CONCLUSIONS: The data demonstrates significant and sustained increase in numbers of referrals. In the short term this was associated with a reduction in referral of elderly patients with stage 5 CKD and an increase in elderly patients with mild renal impairment. In the longer term we saw an increase in referral of an older female population.

Severe hyperkalaemia: demographics and outcome.

BACKGROUND: Few studies have evaluated the prevalence of severe hyperkalaemia in unselected patient populations. We identified all episodes of severe hyperkalaemia occurring in 1 year, and described patient demographics, clinical response and outcome. We also assessed junior doctor knowledge of its causes and significance. MATERIALS AND METHODS: A retrospective interrogation of the database of the regional biochemical laboratory identified all episodes of severe hyperkalaemia (K≥ 6.5 mmol/L) occurring in 2011. The understanding of trainee doctors of the importance, causes and treatment of severe hyperkalaemia was assessed by structured questionnaire. RESULTS: Severe hyperkalaemia was recorded in 433 samples (365 patients) giving a prevalence of 0.11%. Thirty-six per cent of episodes occurred in patients under the care of a nephrologist, who were significantly younger than those not under the care of a nephrologist. In the nephrology cohort, 86% occurred in patients with chronic kidney disease (CKD), the majority of which had CKD Stage 5. In the non-nephrology cohort, only 65% occurred in the context of CKD, which was equally distributed between Stages 3 and 5 CKD. In both patient groups, roughly 50% of episodes occurred in association with acute kidney injury (AKI). Acute mortality (death within 48 h of documented severe hyperkalaemia) was higher in the non-nephrology compared with the nephrology cohort. Time to repeat serum potassium was influenced by the clinical setting with shorter time to repeat for acute care compared with ward settings. Assessment of trainee doctor's knowledge suggested significant deficiencies in relation to severe hyperkalaemia. CONCLUSIONS: The prevalence of severe hyperkalaemia was low and occurred predominantly in the context of CKD and/or AKI. The majority of episodes occurred in patients not under the care of a nephrologist. Variability in time to repeat serum potassium levels suggested deficiencies in care, and assessment of trainee doctor's knowledge suggests the need for further educational initiatives to highlight its importance.

Identifying primary stressors impacting macroinvertebrates in the Salinas River (California, USA): relative effects of pesticides and suspended particles.

Laboratory dose-response experiments with organophosphate and pyrethroid pesticides, and dose-response experiments with increasing particle loads were used to determine which of these stressors were likely responsible for the toxicity and macroinvertebrate impacts previously observed in the Salinas River. Experiments were conducted with the amphipod Hyalella azteca, the baetid mayfly Procloeon sp., and the midge Chironomus dilutus (Shobanov, formerly Chironomus tentans). The results indicate the primary stressor impacting H. azteca was pesticides, including chlorpyrifos and permethrin. The mayfly Procloeon sp. was sensitive to chlorpyrifos and permethrin within the range of concentrations of these pesticides measured in the river. Chironomus dilutus were sensitive to chlorpyrifos within the ranges of concentrations measured in the river. None of the species tested were affected by turbidity as high as 1000 NTUs. The current study shows that pesticides are more important acute stressors of macroinvertebrates than suspended sediments in the Salinas River.

A comparison of in situ and laboratory toxicity tests with the estuarine amphipod Eohaustorius estuarius.

Amphipod survival in laboratory and in situ exposures was assessed using the eastern Pacific Haustoriid species Eohaustorius estuarius. Toxicity test results were compared using intact (unhomogenized) and homogenized sediment samples in both field and laboratory exposures. Experiments were conducted in Moss Landing Harbor, California, an impaired waterbody under 303 (d) of the US Clean Water Act. Synoptic laboratory and in situ sediment toxicity tests were conducted at two stations: Sandholdt Bridge (SB), the most contaminated station in the harbor, and at the South Jetty (SJ), a more marine station near the mouth of the harbor. We found that Eohaustorius is amenable to in situ testing. Despite highly variable field salinity regimes (6-32 PSU at SB and 21-34 PSU at SJ), in situ control survival was 87% and 84% at SB and SJ, respectively. Amphipod survival was lower in the in situ exposures relative to the laboratory exposures at both sites. Survival at SB was 30% and 76% in the homogenized in situ and laboratory samples, respectively, and 40% and 64% in the intact (unhomogenized) in situ and laboratory samples, respectively. Neither the homogenized or intact samples from the SJ station were toxic in laboratory experiments, but amphipod survival was only 40% in the intact in situ exposure at this station, possibly due to predation. These experiments suggest that the interaction of contaminants and variable physical parameters such as salinity and temperature may have resulted in lower survival in the in situ exposures. Sediment homogenization prior to in situ deployment may have reduced effects of predators in some samples.

Integrated assessment of the impacts of agricultural drainwater in the Salinas River (California, USA).

The Salinas River is the largest of the three rivers that drain into the Monterey Bay National Marine Sanctuary in central California. Large areas of this watershed are cultivated year-round in row crops and previous laboratory studies have demonstrated that acute toxicity of agricultural drainwater to Ceriodaphnia dubia is caused by the organophosphate (OP) pesticides chlorpyrifos and diazinon. In the current study, we used a combination of ecotoxicologic tools to investigate incidence of chemical contamination and toxicity in waters and sediments in the river downstream of a previously uncharacterized agricultural drainage creek system. Water column toxicity was investigated using a cladoceran C. dubia while sediment toxicity was investigated using an amphipod Hyalella azteca. Ecological impacts of drainwater were investigated using bioassessments of macroinvertebrate community structure. The results indicated that Salinas River water downstream of the agricultural drain is acutely toxic to Ceriodaphnia, and toxicity to this species was highly correlated with combined toxic units (TUs) of chlorpyrifos and diazinon. Laboratory tests were used to demonstrate that sediments in this system were acutely toxic to H. azteca, which is a resident genus. Macroinvertebrate community structure was moderately impacted downstream of the agricultural drain input. While the lowest macroinvertebrate abundances were measured at the station demonstrating the greatest water column and sediment toxicity and the highest concentrations of pesticides, macroinvertebrate metrics were more significantly correlated with bank vegetation cover than any other variable. Results of this study suggest that pesticide pollution is the likely cause of laboratory-measured toxicity in the Salinas River samples and that this factor may interact with other factors to impact the macroinvertebrate community in the system.

Causes of sediment toxicity to Mytilus galloprovincialis in San Francisco Bay, California.

Since the San Francisco Regional Monitoring Program (RMP) sampling began, elutriate samples prepared with sediment from the Grizzly Bay monitoring station have been consistently toxic to bivalve larvae (Mytilus galloprovincialis). An investigation into the cause of toxicity was initiated with a Phase I Toxicity Identification Evaluation (TIE) using bivalve embryos. TIE results and chemical analyses of elutriate samples suggested that divalent metals were responsible for the observed toxicity. Following the initial characterization of trace metals as toxicants, additional TIEs were performed on elutriates prepared from three additional Grizzly Bay samples collected between 1997 and 2001. Additional TIEs included ethylenediamine tetraacetic acid (EDTA) treatments in a sediment-water interface (SWI) exposure system, and the use of a cation exchange column with serial elution of sample fractions with hydrochloric acid of increasing normality. EDTA significantly reduced toxicity in overlying water in the SWI system. The cation exchange column reduced both toxicity and concentrations of trace metals, and serial elution of the column added back both toxicity and specific metals contained in individual acid fractions. Chemical analyses of three elutriate samples demonstrated copper concentrations were within the range toxic to bivalves. Results of Phase I TIEs, additional Phase II treatments, SWI exposures, and metals analyses indicate the potential for metal toxicity in sediments from this estuarine site. When combined with the results of standard TIE methods, a solid-phase cation extraction and elution approach identified copper as the most probable cause of toxicity.

Causes of ambient toxicity in the Calleguas Creek watershed of southern California.

A combination of toxicity tests, chemical analyses, and Toxicity Identification Evaluations (TIEs) were used to investigate receiving water toxicity in the Calleguas Creek watershed of southern California. Studies were conducted from 1995 through 1999 at various sites to investigate causes of temporal variability of toxicity throughout this system. Causes of receiving water toxicity varied by site and species tested. Investigations in the lower watershed (Revolon Slough, Santa Clara Drain, Beardsley Wash) indicated that toxicity of samples to the cladoceran Ceriodaphnia dubia was due to elevated concentrations of the organophosphate pesticide chlorpyrifos, while causes of intermittent toxicity to fathead minnows (Pimephales promelas) and the alga Selanastrum capricornutum were less clear. Investigations at sites in the middle and upper reaches of the watershed (Arroyo Simi and Conejo Creek) indicated that the pesticide diazinon was the probable cause of receiving water toxicity to Ceriodaphnia. Elevated ammonia was the cause of toxicity to fathead minnows in the upper watershed sites. Results of these and previous studies suggest that biota are impacted by degraded stream quality from a variety of point and non-point pollution sources in the Calleguas Creek watershed. Water quality resource manager's efforts to identify contaminant inputs and implement source control will be improved with the findings of this study.

An evaluation of methods for calculating mean sediment quality guideline quotients as indicators of contamination and acute toxicity to amphipods by chemical mixtures.

Mean sediment quality guideline quotients (mean SQGQs) were developed to represent the presence of chemical mixtures in sediments and are derived by normalizing a suite of chemicals to their respective numerical sediment quality guidelines (SQGs). Mean SQGQs incorporate the number of SQGs exceeded and the degree to which they are exceeded and are used for comparison with observed biological effects in the laboratory or field. The current research makes it clear, however, that the number and type of SQGs used in the derivation of these mean quotients can influence the ability of mean SQGQ values to correctly predict acute toxicity to marine amphipods in laboratory toxicity tests. To determine the optimal predictive ability of mean SQGQs, a total of 18 different chemical combinations were developed and compared. The ability of each set of mean SQGQs to correctly predict the presence and absence of acute toxicity to amphipods was determined using three independent databases (n = 605, 2753, 226). Calculated mean SQGQ values for all chemical combinations ranged from 0.002 to 100. The mean SQGQ that was most predictive of acute toxicity to amphipods is calculated as SQGQ1 = ((sigma ([cadmium]/4.21 )([copper]/270)([lead]/ 12.18)([silver]/1.77)([zinc]/ 410)([total chlordane]/6)([dieldrin]/8)([total PAHoc]/1,800)([total PCB]/400))/9). Both the incidence and magnitude of acute toxicity to amphipods increased with increasing SQGQI values. To provide better comparability between regions and national surveys, SQGQ1 is recommended to serve as the standard method for combination of chemicals and respective SQGs when calculating mean SQGQs.