The Gulf Long-Term Follow-Up Study (GuLF STUDY): Biospecimen collection at enrollment

The 2010 Deepwater Horizon (DWH) explosion in the Gulf of Mexico led to the largest ever marine oil spill by volume. The GuLF STUDY is investigating possible adverse human health effects associated with oil spill activities. One objective of the study was to utilize biological specimens from study participants to examine spill-related adverse health effects. This study describes the methods for collecting, processing, shipping, and storing specimens during the enrollment phase of the study. GuLF STUDY participants living in Gulf States (Alabama, Florida, Louisiana, Mississippi, and eastern Texas) were eligible to complete a home visit at enrollment, one to three years after the DWH explosion. During this visit, blood, urine, toenail and hair clippings, and house dust samples were collected. Specimens were shipped overnight to a central processing laboratory in containers with cold and ambient temperature compartments. Most blood and urine specimens were then aliquoted and stored in liquid nitrogen vapor or at -80°C, with some samples stored at -20°C. A total of 11,193 participants completed a home visit, and over 99% provided at least one biospecimen. Most participants provided blood (93%), urine (99%), and toenail clippings (89%), and 40% provided hair. Nearly all participants (95%) provided house-dust samples. Most samples were received by the laboratory one (58%) or two (25%) days after collection. These biospecimens enable investigation of a range of biomarkers of spill-related adverse health effects, and possibly some biomarkers of spill-related exposures. The biospecimen collection, handling, and storage protocols were designed to maximize current and future scientific value within logistical and budgetary constraints and might serve as a template for future studies conducted in similar time-critical and geographically dispersed settings.

System to monitor a portion of the total testing process in medical clinics and laboratories: evaluation of a split-specimen design

To evaluate a split-specimen design to identify problems in the testing process in hospital and physician office laboratories, we examined the testing for serum total cholesterol (n = 646) and potassium (n = 732) at 11 medical clinics evaluating 30-199 patients (mean, 125). Clinic personnel collected three tubes of blood from each patient. One specimen was processed routinely, the second was sent to a referral laboratory (RL), and the third specimen was sent to a holding facility for storage. The corresponding stored sample was retrieved and divided into three audit samples randomly and when result difference for the first two specimens exceeded critical values; one audit sample was sent to the original participant, the second to the RL, and the third to a referee laboratory. When three criteria were used, the result discrepancy rates were 2.5-8.7% for potassium and 1.5-4.6% for cholesterol. The split-specimen design could be implemented and evaluated as a monitoring system for a portion of the testing process.

System to Monitor a Portion of the Total Testing Process in Medical Clinics and Laboratories: Evaluation of a Split-Specimen Design

To evaluate a split-specimen design to identify problems in the testing process in hospital and physician office laboratories, we examined the testing for serum total cholesterol (n = 646) and potassium (n = 732) at 11 medical clinics evaluating 30–199 patients (mean, 125). Clinic personnel collected three tubes of blood from each patient. One specimen was processed routinely, the second was sent to a referral laboratory (RL), and the third specimen was sent to a holding facility for storage. The corresponding stored sample was retrieved and divided into three audit samples randomly and when result difference for the first two specimens exceeded critical values; one audit sample was sent to the original participant, the second to the RL, and the third to a referee laboratory. When three criteria were used, the result discrepancy rates were 2.5–8.7% for potassium and 1.5–4.6% for cholesterol. The split-specimen design could be implemented and evaluated as a monitoring system for a portion of the testing process.

A system to monitor a portion of the total testing process in medical clinics and laboratories: feasibility of a split-specimen design

OBJECTIVE

The purpose of this study was to assess the feasibility of using a prototype split-specimen design to assess integrity of a portion of the total testing process in medical clinics and laboratories.

DESIGN

Two or three tubes of venous blood were collected from 177 patients for analysis of one of three analytes (serum potassium, serum total cholesterol, and whole-blood hemoglobin). Patients were seen at one of the nine clinics participating in this study. In all cases, one tube of blood from each patient was sent to a commercial referral laboratory, and the other tube(s) forwarded to the laboratory that routinely tested specimens for the clinic (participating laboratory) for analysis. Each participating laboratory removed a preanalysis and sometimes a post-analysis aliquot from each specimen and forwarded these to the referral laboratory for analysis.

SETTING

The study was conducted in six physician office laboratories (three serving 1 to 4 [mean, 2.7] internists and three serving 3 to 24 [mean, 12] family physicians) and three hospital laboratories (serving hospitals with 100 to more than 700 beds).

PATIENTS

Study patients were voluntary participants and provided informed consent. Patient age ranged from 18 to 80 years, and for all the laboratory test was specifically ordered for clinical reasons. Patients who were unable or unwilling to provide informed consent, those for whom testing would require that they provide more than 100 mL of blood, those whose blood was being collected by fingerstick, and those with results that were part of a laboratory test profile were excluded.

MAIN OUTCOME MEASURES

Two main outcome measures were assessed: (1) percent differences between split-specimen results exceeding the maximum allowable imprecision level, which was based on published biological variation data (defined as one-half of the intraindividual percent coefficient of variation), for each analyte (result discrepancies); and (2) all "problems" (defined as departures from standard operating procedures) that could be documented by retrospective review of all relevant medical and laboratory records.

RESULTS

The rate of result discrepancies was 1 in 20 (5%) for patients in whom hemoglobin was analyzed, 12 in 57 (21%) for patients in whom potassium was analyzed, and 1 in 60 (2%) for patients in whom total cholesterol was analyzed. Results of samples obtained during the aliquoting and storage phases of the total testing process were subject to study-induced problems and were generally not useful in tracing problems to specific stages of the testing process. A total of 28 problems (involving 26 patients) were documented, but only 6 problems were due to routine testing processes.

CONCLUSIONS

The feasibility and limitations of a split-specimen design to detect result discrepancies were demonstrated. Most documented problems (22 of 28, or 79%) were study induced. To assess integrity of the total testing process, such problems need to be avoided.

Accuracy of reporting nosocomial infections in intensive-care-unit patients to the National Nosocomial Infections Surveillance System: a pilot study

OBJECTIVE

To assess the accuracy of nosocomial infections data reported on patients in the intensive-care unit by nine hospitals participating in the National Nosocomial Infections Surveillance (NNIS) System.

DESIGN

A pilot study was done in two phases to review the charts of selected intensive-care-unit patients who had nosocomial infections reported to the NNIS System. The charts of selected high- and low-risk patients in the same cohort who had no infections reported to the NNIS System also were included. In phase I, trained data collectors reviewed a sample of charts for nosocomial infections. Retrospectively detected infections that matched with previously reported infections were deemed to be true infections. In phase II, two Centers for Disease Control and Prevention (CDC) epidemiologists reexamined a sample of charts for which a discrepancy existed. Each sampled infection either was confirmed or disallowed by the epidemiologists. Confirmed infections also were deemed to be true infections. True infections from both phases were used to estimate the accuracy of reported NNIS data by calculating the predictive value positive, sensitivity, and specificity at each major infection site and the "other sites."

RESULTS

The data collectors examined a total of 1,136 patients' charts in phase I. Among these charts were 611 infections that the study hospitals had reported to the CDC. The data collectors retrospectively matched 474 (78%) of the prospectively identified infections, but also detected 790 infections that were not reported prospectively. Phase II focused on the discrepant infections: the 137 infections that were identified prospectively and reported but not detected retrospectively, and the 790 infections that were detected retrospectively but not reported previously. The CDC epidemiologists examined a sample of 113 of the discrepant reported infections and 369 of the discrepant detected infections, and estimated that 37% of all discrepant reported infections and 43% of all discrepant detected infections were true infections. The predictive value positive for reported bloodstream infections, pneumonia, surgical-site infection, urinary tract infection, and other sites was 87%, 89%, 72%, 92%, and 80%, respectively; the sensitivity was 85%, 68%, 67%, 59%, and 30%, respectively; and the specificity was 98.3%, 97.8%, 97.7%, 98.7%, and 98.6%, respectively.

CONCLUSIONS

When the NNIS hospitals in the study reported a nosocomial infection, the infection most likely was a true infection, and they infrequently reported conditions that were not infections. The hospitals also identified and reported most of the nosocomial infections that occurred in the patients they monitored, but accuracy varied by infection site. Primary bloodstream infection was the most accurately identified and reported site. Measures that will be taken to improve the quality of the infection data reported to the NNIS System include reviewing the criteria for definitions of infections and other data fields, enhancing communication between the CDC and NNIS hospitals, and improving the training of surveillance personnel in NNIS hospitals.