| 1. |
- Grankvist, Kjell, et al.
(författare)
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Laboratoriernas verksamhet
- 2018. - 10
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Ingår i: Laurells Klinisk kemi i praktisk medicin. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 13-30
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Bokkapitel (refereegranskat)
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| 2. |
- Hammarsten, Ola, et al.
(författare)
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Risk of myocardial infarction at specific troponin T levels using the parameter predictive value among lookalikes (PAL)
- 2017
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Ingår i: Clinical Biochemistry. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0009-9120 .- 1873-2933. ; 50:1-2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Myocardial infarction is more likely if the heart damage biomarker cardiac troponin T (cTnT) is elevated in a blood sample, indicating that cardiac damage has occurred. No method allows the clinician to estimate the risk of myocardial infarction at a specific cTnT level in a given patient. Methods: Predictive value among lookalikes (PAL) uses pre-test prevalence, sensitivity and specificity at adjacent cTnT limits based on percentiles. PAL is the pre-test prevalence-adjusted probability of disease between two adjacent cTnT limits. If a chest pain patients cTnT level is between these limits, the risk of myocardial infarction can be estimated. Results: The PAL based on percentiles had an acceptable sampling error when using 100 bootstrapped data of 18 different biomarkers from 38,945 authentic lab measurements. A PAL analysis of an emergency room cohort (n = 11,020) revealed that the diagnostic precision of a high-sensitive cTnT assay was similar among chest pain patients at different ages. The higher incidence of false positive results due to non-specific increases in cTnT in the high-age group was counterbalanced by a higher pre-test prevalence of myocardial infarction among older patients, a finding that was missed when using a conventional ROC plot analysis. Conclusions: The PAL was able to calculate the risk of myocardial infarction at specific cTnT levels and could complement decision limits. 2016 The Authors. The Canadian Society of Clinical Chemists. Published by Elsevier Inc.
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| 3. |
- Hammarsten, Ola, et al.
(författare)
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Tolkning av analysresultat
- 2018. - 10
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Ingår i: Laurells Klinisk kemi i praktisk medicin. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 31-53
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Bokkapitel (refereegranskat)
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| 4. |
- Löwbeer, Christian, et al.
(författare)
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Energiomsättning, diabetes och lipoproteinrubbningar
- 2018. - 10
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Ingår i: Laurells klinisk kemi i praktisk medicin. - Lund : Studentlitteratur AB. - 9789144119748 ; , s. 345-414
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Ognissanti, Damiano, et al.
(författare)
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Cardiac troponin T concentrations and patient-specific risk of myocardial infarction using the novel PALfx parameter
- 2019
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 1873-2933 .- 0009-9120. ; 66, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Myocardial infarction (MI) is more likely if the heart damage biomarker cardiac troponin T (cTnT) is elevated in a blood sample from a patient with chest pain. There is no conventional method to estimate the risk of MI at a specific cTnT concentration. The purpose of this study was to evaluate the performance of a novel method that converts cTnT concentrations to patient-specific risks of MI. Methods: Admission cTnT measurements in 15,425 ED patients from three hospitals with a primary complaint of chest pain, with or without a clinical diagnosis of MI, were Box-Cox-transformed to normality density functions to calculate the percentage with MI among patients with a given cTnT concentration, the parametric predictive value among lookalikes (PALfx). The ability of the PALfx to generate stable risk estimates of MI was examined by bootstrapping and expressed as the coefficient of variation (CV). Results: Four age and sex-specific subgroups above or below 60 years of age with distinct cTnT distributions were identified among patients without MI. The cTnT distributions across subgroups with MI were similar, allowing us to use all admissions with MI to calculate the PALfx in the four subgroups. For instance, at a baseline cTnT concentration of 7 ng/L, a female patient < 60 years would have a 0.5% risk of MI whereas a male patient > 60 years would have a 1.9% risk of MI. To assess the stability of the PALfx method we bootstrapped smaller and smaller subsets of the 15,422 ED visits. We found that 1950 patients without MI and 50 patients with MI were sufficient to limit the variation of the PALfx with a CV of 0.8–5.4%, close to the CV using the entire dataset. The MI risk estimates were similar when data from the three hospitals were used separately to derive the PALfx equations. Conclusions: The PALfx can be used to estimate the risk of MI at patient-specific cTnT concentrations with acceptable margins of error. The patient-specific risk of disease using the PALfx could complement decision limits.
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| 6. |
- Ognissanti, Damiano, et al.
(författare)
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Estimating Analytical Errors of Glomerular Filtration Rate Measurement
- 2022
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 68:9, s. 1211-1218
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Tidskriftsartikel (refereegranskat)abstract
- Background Few studies are available on how to optimize time points for sampling and how to estimate effects of analytical uncertainty when glomerular filtration rate (GFR) is calculated. Methods We explored the underlying regression mathematics of how analytical variation of a kidney filtration marker affects 1-compartment, slope-and-intercept GFR calculations, using 2 or 3 time points following a bolus injection, and used this to examine the results from 731 routine 3-point iohexol plasma clearance measurements. Results GFR calculations inflated analytical uncertainty if the time points were taken too late after the bolus injection and too close after each other. The uncertainty in GFR calculation was, however, the same as the analytical uncertainty if optimal time points were used. The middle of the 3 samples was of little value. The first sample should be taken as early as possible after the distribution phase. Sampling before the patient specific half-life of the kidney filtration marker resulted in an exponential error inflation whereas no error inflation was seen when sampling occurred later than 2 half-lives. Theoretical GFR uncertainty could be lowered 2.6-fold if individually optimized time points for sampling had been used in our 731 clearance measurements. Using Taylor expansions to approximate the moments of transformed random variables, the uncertainty of an individual GFR measurement could be calculated in a simple enough way to be applicable by laboratory software. Conclusions We provide a theoretical foundation to select patient-optimal time points that may both limit errors and allow calculation of GFR uncertainty.
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| 7. |
- von Otter, Malin, 1978, et al.
(författare)
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Genetic associations of Nrf2-encoding NFE2L2 variants with Parkinson's disease: a multicenter study
- 2014
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Ingår i: BMC Medical Genetics. - : Springer Science and Business Media LLC. - 1471-2350. ; 15:1, s. artikel nr 131-
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Tidskriftsartikel (refereegranskat)abstract
- Background: The transcription factor Nrf2, encoded by the NFE2L2 gene, is an important regulator of the cellular protection against oxidative stress. Parkinson s disease is a neurodegenerative disease highly associated with oxidative stress. In a previously published study, we reported associations of NFE2L2 haplotypes with risk and age at onset of idiopathic Parkinson s disease in a Swedish discovery material and a Polish replication material. Here, we have extended the replication study and performed meta-analyses including the Polish material and four new independent European patient-control materials. Furthermore, all SNPs included in the haplotype windows were investigated individually for associations with Parkinson s disease in meta-analyses including all six materials.Methods: Totally 1038 patients and 1600 control subjects were studied. Based on previous NFE2L2 haplotype associations with Parkinson s disease, five NFE2L2 tag SNPs were genotyped by allelic discrimination and three functional NFE2L2 promoter SNPs were genotyped by sequencing. The impact of individual SNPs and haplotypes on risk and age at onset of Parkinson s disease were investigated in each material individually and in meta-analyses of the obtained results.Results: Meta-analyses of NFE2L2 haplotypes showed association of haplotype GAGCAAAA, including the fully functional promoter haplotype AGC, with decreased risk (OR = 0.8 per allele, p = 0.012) and delayed onset (+ 1.1 years per allele, p = 0.048) of Parkinson s disease. These results support the previously observed protective effect of this haplotype in the first study. Further, meta-analyses of the SNPs included in the haplotypes revealed four NFE2L2 SNPs associated with age at onset of Parkinson s disease (rs7557529 G > A, -1.0 years per allele, p = 0.042; rs35652124 A > G, -1.1 years per allele, p = 0.045; rs2886161 A > G, -1.2 years per allele, p = 0.021; rs1806649 G > A, + 1.2 years per allele, p = 0.029). One of these (rs35652124) is a functional SNP located in the NFE2L2 promoter. No individual SNP was associated with risk of Parkinson s disease.Conclusion: Our results support the hypothesis that variation in the NFE2L2 gene, encoding a central protein in the cellular protection against oxidative stress, may contribute to the pathogenesis of Parkinson s disease. Functional studies are now needed to explore these results further.
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