Comparison of lactate values between point-of-care and central laboratory analyzers

Measurement of lactate levels is important in the care of critically ill adult and pediatric patients. We compared 3 whole blood lactate methods (Radiometer ABL 725, Radiometer Medical A/S, Bronshoj, Denmark; i-STAT, i-STAT, East Windsor, NJ; and Nova Lactate Plus, Nova Biomedical, Waltham, MA) with 2 plasma-based methods (Roche Integra, Roche Diagnostics, Indianapolis, IN; and Vitros, Ortho Clinical Diagnostics, Rochester, NY). The Vitros LAC slide assay was used as the reference method. Results were compared by least squares regression and Bland-Altmann plots and by comparing concordance within clinically relevant lactate ranges. Correlation between lactate methods was good with slopes between 0.87 and 1.06 and intercepts of 0.9 to 1.8 mg/dL (0.1-0.2 mmol/L) of lactate for all 4 methods compared with the Vitros. At high (>54.1 mg/dL [6 mmol/L]) lactate values, the Radiometer and i-STAT methods reported lower lactate results compared with the Vitros and Integra. The Nova analyzer reported higher lactate results than either the Vitros or Integra. The negative bias in i-STAT and Radiometer results may confound the interpretation of patient condition if multiple methods are used within the same institution.     

Results of a phase I/II trial of recombinant human granulocyte- macrophage colony-stimulating factor in very low birthweight neonates: significant induction of circulatory neutrophils, monocytes, platelets, and bone marrow neutrophils

Neonates, especially those of very low birthweight (VLBW), have an increased risk of nosocomial infections secondary to deficiencies in development. We previously demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) production and mRNA expression from stimulated neonatal mononuclear cells are significantly less than that from adult cells. Recombinant murine GM-CSF administration to neonatal rats has resulted in neutrophilia, increased neutrophil production, and increased survival of pups during experimental Staphylococcus aureus sepsis. In the present study, we sought to determine the safety and biologic response of recombinant human (rhu) GM-CSF in VLBW neonates. Twenty VLBW neonates (500 to 1,500 g), aged < 72 hours, were randomized to receive either placebo (n = 5) or rhuGM-CSF at 5.0 micrograms/kg once per day (n = 5), 5.0 micrograms/kg twice per day (n = 5), or 10 micrograms/kg once per day (n = 5) given via 2-hour intravenous infusion for 7 days. Complete blood counts, differential, and platelet counts were obtained, and tibial bone marrow aspirate was performed on day 8. Neutrophil C3bi receptor expression was measured at 0 and 24 hours. GM-CSF levels were measured by a sandwich enzyme-linked immunosorbent assay at 2, 4, 6, 12, and 24 hours after the first dose of rhuGM-CSF. At all doses, rhuGM-CSF was well tolerated, and there was no evidence of grade III or IV toxicity. Within 48 hours of administration, there was a significant increase in the circulating absolute neutrophil count (ANC) at 5.0 micrograms/kg twice per day and 10.0 micrograms/kg once per day, which continued for at least 24 hours after discontinuation of rhuGM-CSF. When the ANC was normalized for each patient's first ANC, there was a significant increase in the ANC on days 6 and 7 at each dose level. By day 7, all tested doses of rhuGM- CSF resulted in an increase in the absolute monocyte count (AMC) compared with placebo-treated neonates. In those receiving rhuGM-CSF 5.0 micrograms/kg twice per day, there was additionally a significant increase in the day 7 and 8 platelet count. Tibial bone marrow aspirates demonstrated a significant increase in the bone marrow neutrophil storage pool (BM NSP) at 5.0 micrograms/kg twice per day and 10.0 micrograms/kg once per day. Neutrophil C3bi receptor expression was significantly increased 24 hours after the first dose of rhuGM-CSF at 5.0 micrograms/kg once per day. The elimination half-life (T1/2) of rhuGM-CSF was 1.4 +/- 0.8 to 3.9 +/- 2.8 hours.(ABSTRACT TRUNCATED AT 400 WORDS)     

Molecular analysis of relapse in chronic myeloid leukemia after allogeneic bone marrow transplantation

Four patients with Philadelphia (Ph') positive chronic myeloid leukemia (CML) were studied before, after, and on relapse following allogeneic bone marrow transplantation (BMT). Southern analysis of DNA from cells collected before and at relapse after BMT was performed in order to investigate the origin of the leukemia at relapse. Using minisatellite probes we showed that the relapse occurred in cells of host origin in all four patients and this was confirmed with a Y chromosome specific probe in two male patients who had a female donor. Furthermore, using two probes for the breakpoint cluster region (bcr) on chromosome 22, we showed that leukemic cells at relapse bore identical rearrangements to those in the disease at time of presentation of each patient. We conclude that relapse in all four patients is due to re-emergence of the original leukemic clone.     

Testing measurement invariance of the patient-reported outcomes measurement information system pain behaviors score between the US general population sample and a sample of individuals with chronic pain

Purpose

In order to test the difference between group means, the construct measured must have the same meaning for all groups under investigation. This study examined the measurement invariance of responses to the patient-reported outcomes measurement information system (PROMIS) pain behavior (PB) item bank in two samples: the PROMIS calibration sample (Wave 1, N = 426) and a sample recruited from the American Chronic Pain Association (ACPA, N = 750). The ACPA data were collected to increase the number of participants with higher levels of pain.

Methods

Multi-group confirmatory factor analysis (MG-CFA) and two item response theory (IRT)-based differential item functioning (DIF) approaches were employed to evaluate the existence of measurement invariance.

Results

MG-CFA results supported metric invariance of the PROMIS–PB, indicating unstandardized factor loadings with equal across samples. DIF analyses revealed that impact of 6 DIF items was negligible.

Conclusions

Based on the results of both MG-CFA and IRT-based DIF approaches, we recommend retaining the original parameter estimates obtained from the combined samples based on the results of MG-CFA.

     

Exploratory and confirmatory factor analysis of the PROMIS pain quality item bank

Purpose

The assessment of pain sensation and quality is a key component in understanding the experience of individuals with chronic pain. This study evaluated the factor structure of the patient-reported outcome measurement information system (PROMIS) pain quality item bank.

Methods

As part of the PROMIS project, we developed a pool of 37 pain quality items, based on a review of existing pain questionnaires and development of new items. A web-based survey was designed and completed by 845 members of the general population and 967 individuals with different types of chronic pain. Exploratory factor analysis (EFA) was conducted on a random split-half sample of the data to examine the factor structure of the 37 PROMIS pain quality items in the general population and in a chronic pain sample. A confirmatory factor analysis was conducted in the holdout sample.

Results

The EFA of the pain quality items resulted in comparable six-factor solutions for the general and chronic pain samples: (1) pulling/tugging pain; (2) tingling/numbness pain; (3) sharp/stabbing pain; (4) dull/aching pain; (5) pounding/pulsing pain; and (6) affective pain. The confirmatory factor analysis in the holdout sample supported this factor structure.

Conclusions

Further research is needed to evaluate the psychometric characteristics of the derived scales based on their factor scores.     

Setting standards for severity of common symptoms in oncology using the PROMIS item banks and expert judgment

Background

Although the use of patient-reported outcome measures (PROs) has increased markedly, clinical interpretation of scores remains lacking. We developed a method to identify clinical severity thresholds for pain, fatigue, depression, and anxiety in people with cancer.

Methods

Using available Patient-Reported Outcomes Measurement Information System (PROMIS) item bank response data collected on 840 cancer patients, symptom vignettes across a range of symptom severity were developed and placed on index cards. Cards represented symptom severity at five-point intervals differences on the T score metric [mean = 50; standard deviation (SD) = 10]. Symptom vignettes for each symptom were anchored on these standardized scores at 0.5 SD increments across the full range of severity. Clinical experts, blind to the PROMIS score associated with each vignette, rank-ordered the vignettes by severity, then arrived at consensus regarding which two vignettes were at the upper and lower boundaries of normal and mildly symptomatic for each symptom. The procedure was repeated to identify cut scores separating mildly from moderately symptomatic, and moderately from severely symptomatic scores. Clinician severity rankings were then compared to the T scores upon which the vignettes were based.

Results

For each of the targeted PROs, the severity rankings reached by clinician consensus perfectly matched the numerical rankings of their associated T scores. Across all symptoms, the thresholds (cut scores) identified to differentiate normal from mildly symptomatic were near a T score of 50. Cut scores differentiating mildly from moderately symptomatic were at or near 60, and those separating moderately from severely symptomatic were at or near 70.

Conclusions

The study results provide empirically generated PROMIS T score thresholds that differentiate levels of symptom severity for pain interference, fatigue, anxiety, and depression. The convergence of clinical judgment with self-reported patient severity scores supports the validity of this methodology to derive clinically relevant symptom severity levels for PROMIS symptom measures in other settings.