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Cited by 67Blood Coagulation and Thrombosis MechanismsClinical Laboratory Practices and Quality ControlBlood properties and coagulation

A “Percent Correction” Formula for Evaluation of Mixing Studies

Open access
Chang, Sheng-hsiung, Tillema, Veronica, Scherr, Doris·2002·American Journal of Clinical Pathology
DOI 10.1309/rrek-8l6m-d2kc-hwlh
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Abstract

The study examined a "percent correction" formula for evaluating mixing study results comparing a 1:1 mix with a new 4:1 mix of patient plasma with citrated normal plasma for a prolonged activated partial thromboplastin time (aPTT) and/or prothrombin time (PT). The study also examined 3 suggested definitions of correction for evaluating mixing study results for comparison. Applicability of percent correction for evaluating the aPTT 4:1 mix testing with and without incubation also was studied. Our results showed that percent correction of the aPTT or PT 4:1 mix had an overall good sensitivity and specificity for detecting anticoagulant and factor deficiency and was better than that of the aPTT or PT 1:1 mix. The 3 suggested definitions of correction all had a poor sensitivity for detecting anticoagulant. The percent correction of the aPTT 4:1 mix testing after incubation had better sensitivity and specificity that that of testing immediately. Nevertheless, these procedures were complementary to each other. The percent correction using the aPTT or PT 4:1 mix seemed to offer a simple, objective, and effective criterion for evaluating mixing study results.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper evaluates a “percent correction” formula for 1:1 and 4:1 patient/normal plasma mixing studies in prolonged PT and/or aPTT, finding the 4:1 mix better than the 1:1 mix for detecting anticoagulant and factor deficiency. For aPTT 4:1 testing, incubation improved sensitivity and specificity to 100% each in the part 2 study, but immediate and incubated procedures were complementary.

Key findings

  • For aPTT 4:1 mix with percent correction cutoff ≥50%, part 1 showed anticoagulant sensitivity 100% and specificity 88%; factor deficiency cases correctly classified 22/25 (88%) with specificity 100%. The aPTT 1:1 original cutoffs (>70%/<58%) had anticoagulant sensitivity 33% and specificity 100%, with only 4/15 (27%) anticoagulant cases correctly classified.
  • For PT 4:1 mix with cutoff >40%, anticoagulant sensitivity was 100% and specificity 96%; factor deficiency cases correctly classified 23/24 (96%) with specificity 100%. PT 1:1 original cutoffs (>75%/<70%) had anticoagulant sensitivity 50% and specificity 95%.
  • The 3 suggested definitions of correction for aPTT 1:1 had poor sensitivity for detecting anticoagulant: upper limit of normal 13%, CNP aPTT +5 seconds 7%, and Rosner index ≤15 7%.
  • In part 2, aPTT 4:1 immediate testing with cutoff ≥50% had anticoagulant sensitivity 91% and specificity 75%; after 60-minute incubation with cutoff >10%, sensitivity and specificity were each 100% for anticoagulant and factor deficiency.

Methods

  • Part 1 included 51 samples: 30 patient samples received for mixing studies, 5 samples from patients receiving oral anticoagulant therapy with INRs 2.1–4.0, and 16 artificially prepared factor-deficient samples covering severe and mild deficiencies of factors II, V, VII, VIII, IX, X, XI, and XII. Part 2 included 24 samples: 7 mixing-study samples, 5 oral anticoagulant samples with INRs 2.5–3.6, 6 artificially prepared factor-deficient samples for factors V, VIII, and IX, and 6 circulating anticoagulant samples including 1 factor VIII inhibitor and 5 documented lupus anticoagulant samples.
  • Samples were classified into factor deficiency, indeterminate, or circulating anticoagulant groups based on follow-up results: factor assay <50% for factor deficiency; positive DRVVT and/or PTT-LA for circulating anticoagulant; factor assay >50% and negative DRVVT/PTT-LA for indeterminate.
  • PT and aPTT mixing studies used 1:1 and 4:1 mixtures of patient plasma with citrated normal plasma; percent correction was calculated, cutoffs were selected by dot plots, and sensitivity/specificity were calculated excluding indeterminate and borderline cases. Part 2 aPTT 4:1 mixes were tested immediately and after 60 minutes of incubation at 37°C. The 3 suggested definitions of correction were also compared.

Limitations

  • Stated: whether the percent correction procedure applies to other instrument/reagent combinations is an open question; each laboratory must establish its own reference cutoff values; 20 to 30 samples each of anticoagulant and factor deficiency cases probably suffice for establishing cutoffs; no incubation study of PT was performed.
  • Evident: sample sizes were small (51 samples in part 1 and 24 in part 2), and artificially prepared factor-deficient samples were used, which may limit generalizability. Indeterminate cases and borderline percent corrections were excluded from sensitivity/specificity calculations, which may affect the reported estimates.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1309/rrek-8l6m-d2kc-hwlh

Cites

11 of 11 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

3 of 20 cited sources checked · 1 supported · 0 flagged · accuracy not yet measured

  • Findingown data
    § A "Percent Correction" Formula for Evaluation of Mixing Studies

    For identifying anticoagulant and factor deficiency, the percent correction calculated from the 4:1 mixture of patient plasma and citrated normal plasma had good overall sensitivity and specificity for both aPTT and PT.

    “Our results showed that percent correction of the aPTT or PT 4:1 mix had an overall good sensitivity and specificity for detecting anticoagulant and factor deficiency and was better than that of the aPTT or PT 1:1 mix.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The follow-up laboratory results and available information used to classify samples correctly identify whether a sample has a factor deficiency or a circulating anticoagulant.
  • Findingown data

    In the aPTT 1:1 mixing study, the three suggested definitions of correction had poor sensitivity for detecting anticoagulant: 13%, 7%, and 7%.

    “As shown in Table 7, all 3 suggested definitions of correction for evaluating the aPTT 1:1 mix 3 showed poor sensitivity (13%, 7%, and 7%, respectively) for detecting anticoagulant.”
    • Also stated in: § Conclusion · plain
      “The 3 definitions of correction suggested by Brandt et al 3 showed a poor sensitivity for detecting anticoagulant in our study.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] Kaczor DA, Bickford NN, Triplett DA. Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing. Am J Clin Pathol. 1991;95:408-411. source
  • Findingown data

    The study showed that percent correction for the aPTT or PT 4:1 mix had overall good sensitivity and specificity for detecting anticoagulant and factor deficiency.

    “The study showed that the percent correction for the aPTT or PT 4:1 mix had an overall good sensitivity and specificity for detecting anticoagulant and factor deficiency.”
    Quote in the paperSubstantial claim
  • Findingown data

    The authors' results for the aPTT 1:1 mix with original cutoffs greater than 70% and less than 58% showed very poor sensitivity (33%) for detecting anticoagulant.

    “Our results for the aPTT 1:1 mix with percent correction cutoff at more than 70% and at less than 58% (original criteria) (Figure 1 and Table 4) showed a very poor sensitivity (33%) for detecting anticoagulant”
    Quote in the paperSubstantial claim
  • Findingown data

    For the aPTT 4:1 mix tested after incubation, the selected percent correction cutoff of 10% was much lower than the cutoff for immediate testing.

    “For aPTT 4:1 mix testing after incubation, the selected percent correction cutoff of 10% was much lower than that for 4:1 mix immediate testing.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 10
  • May combine two claims. 19
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    It was not clear from the publications which of the 1:1 or 4:1 mixing procedures was preferred.

    “However, it was not clear from the publications which of the 2 procedures was preferred.”
    Quote in the paperNot a substantial claim1 of 4 sources checked
    • cites [2] Chang S, Tillema V. Mixing study procedure changes. Laboratory News Update Marshfield Laboratories. March 8, 1994;17(3):1-7.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [3] Kaczor DA, Bickford NN, Triplett DA. Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing. Am J Clin Pathol. 1991;95:408-411. source
    • cites [7] Bockenstedt PL. Evaluation of a prolonged prothrombin or activated partial thromboplastin time. In: Loscalzo J, Schafer AI, eds. Thrombosis and Hemorrhage. 2nd ed. Baltimore, MD: Williams &amp; Wilkins; 1998:522-523. source
    • cites [8] Triplett DA. Laboratory diagnosis of lupus anticoagulant. Semin Thromb Hemost. 1990;16:182-192. source

      In “FIG. 1. Approach to prolonged APTT” (page unavailable), the paper says most laboratories use a 1:1 mix, while a 4:1 mix is more sensitive when APTT is minimally prolonged. This supports a condition-dependent distinction rather than one universally preferred procedure, but the paper does not say that the publications left the preference unclear. (LLM, conf=0.78)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    The normal range is usually used as a guide for correction but is often inadequate because a circulating anticoagulant with minimally prolonged PT or aPTT may be corrected to normal in a 1:1 mix.

    “The normal range usually is used as the guide for correction.However, it often is inadequate because a circulating anticoagulant with a minimally prolonged PT or aPTT may be corrected to normal in a 1:1 mix of PP with CNP. 8”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [8] Triplett DA. Laboratory diagnosis of lupus anticoagulant. Semin Thromb Hemost. 1990;16:182-192. source

      In “FIG. 1. Approach to prolonged APTT” (page unavailable), the paper says a 1:1 mix of lupus-anticoagulant plasma and normal plasma can correct to within the normal range, particularly with a borderline APTT. It also warns that correction can be hard to distinguish from dilution when the APTT is minimally prolonged. These passages support the concern about using the normal range to judge correction for APTT, but do not establish the same point for PT. (LLM, conf=0.85)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    This phenomenon has been termed the lupus cofactor effect.

    “This phenomenon has been termed the lupus cofactor effect.8,9”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [8] Triplett DA. Laboratory diagnosis of lupus anticoagulant. Semin Thromb Hemost. 1990;16:182-192. source
    • cites [9] Rivard GE, Schiffman S, Rapaport SI. Cofactor of the "lupus anticoagulant." Thromb Diath Haemorrh. 1974;32:554-563. source

  • May combine two claims.

    Findingown data

    For the aPTT 4:1 mixture with a cutoff of 50% or more, anticoagulant sensitivity was 100% (15/15) and specificity was 88%.

    “4:1 % Correction cutoff at 50% or more Factor deficiency 22/25 88% 100 Anticoagulant 15/15 100% 88”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The follow-up laboratory results and available information used to classify samples correctly identify whether a sample has a factor deficiency or a circulating anticoagulant.

  • The quote only partly states this claim.

    Findingown data

    Review of Figures 2 and 5 showed a similar pattern of percent correction distribution between part 1 and part 2.

    “Furthermore, review of Figures 2 and 5 showed a similar pattern of percent correction distribution.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    For the aPTT 1:1 mixture with the original cutoffs, factor deficiency sensitivity was 100% (22/22) and specificity was 33%.

    “1.1 % Correction cutoff at >70% and at <58% Factor deficiency 22/25 (88%) 22/22 (100%) 33 (original criteria) Anticoagulant 4/15 (27%) 4/12 (33%) 100”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The follow-up laboratory results and available information used to classify samples correctly identify whether a sample has a factor deficiency or a circulating anticoagulant.

  • May combine two claims.

    Findingown data

    The aPTT 4:1 mix tested after incubation with a percent correction cutoff greater than 10% had 100% sensitivity and 100% specificity for detecting anticoagulant, compared with 91% and 75% for immediate testing with cutoff 50% or more.

    “The sensitivity and specificity of the aPTT 4:1 mix tested after incubation with the percent correction cutoff at more than 10% were each 100% for detecting anticoagulant compared with 91% and 75% for the aPTT 4:1 mix tested immediately with the percent correction cutoff of 50% or more.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the PT 4:1 mixing study, using a percent correction cutoff greater than 40%, sensitivity for detecting anticoagulant was 100% and specificity was 96%.

    “As in the aPTT 4:1 mix, the results for the PT 4:1 mix with a percent correction cutoff at more than 40% showed markedly improved sensitivity (100%) for detecting anticoagulant while maintaining very good specificity (96%).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    For the aPTT 4:1 mixture with a cutoff of 50% or more, factor deficiency sensitivity was 88% (22/25) and specificity was 100%.

    “4:1 % Correction cutoff at 50% or more Factor deficiency 22/25 88% 100 Anticoagulant 15/15 100% 88”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The follow-up laboratory results and available information used to classify samples correctly identify whether a sample has a factor deficiency or a circulating anticoagulant.

  • May combine two claims.

    Findingown data

    In part 2, 8 of 10 lupus anticoagulant cases showed the lupus cofactor effect after incubation, whereas none of those cases and only 1 of 15 lupus anticoagulant cases in part 1 showed the effect on immediate testing.

    “An additional interesting observation was that in the part 2 study, 8 of 10 cases (cases 52, 53, 55, 57, 71, 72, 73, and 74) with lupus anticoagulant showed the lupus cofactor effect after incubation, while none of those cases and only 1 case (case 30) of 15 cases with lupus anticoagulant in the part 1 study showed the lupus cofactor effect on immediate testing.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    For the aPTT 1:1 mixture with the original cutoffs, anticoagulant sensitivity was 33% (4/12) and specificity was 100%.

    “1.1 % Correction cutoff at >70% and at <58% Factor deficiency 22/25 (88%) 22/22 (100%) 33 (original criteria) Anticoagulant 4/15 (27%) 4/12 (33%) 100”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The follow-up laboratory results and available information used to classify samples correctly identify whether a sample has a factor deficiency or a circulating anticoagulant.

  • May combine two claims.

    Findingown data

    The aPTT 4:1 mix with a percent correction cutoff of 50% or more showed markedly improved sensitivity (100%) for detecting anticoagulant while maintaining good specificity (88%).

    “Results of the aPTT 4:1 mix with percent correction cutoff at 50% or more (Figure 2 and Table 4) showed markedly improved sensitivity (100%) for detecting anticoagulant while maintaining a good specificity (88%).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the part 2 aPTT 4:1 immediate testing, case 70 with factor VIII inhibitor had a percent correction greater than 50% and was classified as factor deficiency.

    “Case 70 with factor VIII inhibitor had a percent correction of more than 50% and was classified as factor deficiency on immediate testing.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    One lupus anticoagulant sample (case 30) had a percent correction of -13% because the aPTT was more prolonged on the mixture than on patient plasma alone.

    “One sample with a lupus anticoagulant (case 30) had a percent correction of -13% resulting from a more prolonged aPTT on the mixture than on the patient plasma alone.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A similar incubation effect in an aPTT mixing study of factor VIII inhibitor has been described.

    “A similar incubation effect in an aPTT mixing study of factor VIII inhibitor has been described.3,10”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [3] Kaczor DA, Bickford NN, Triplett DA. Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing. Am J Clin Pathol. 1991;95:408-411. source
    • cites [10] Kasper CK. Laboratory tests for factor VIII inhibitors, their variation, significance, and interpretation. Blood Coagul Fibrinolysis. 1991;2(suppl 1):7-10.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation
    § A "Percent Correction" Formula for Evaluation of Mixing Studies

    Some anticoagulants have a time-dependent inhibitor effect in mixing studies.

    “In addition, applicability of percent correction for evaluating the aPTT 4:1 mix testing after incubation also was studied to ascertain the described time-dependent inhibitor effect of some anticoagulants in mixing studies.3”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [3] Kaczor DA, Bickford NN, Triplett DA. Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing. Am J Clin Pathol. 1991;95:408-411. source

  • May combine two claims.

    Interpretationown data

    Incubation of the mixture seemed to enhance the lupus cofactor effect and made lupus anticoagulant samples more distinct from factor deficiency samples.

    “Incubation of the mixture seemed to enhance the lupus cofactor effect and made samples with a lupus anticoagulant more distinct from samples with a factor deficiency.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premiseown data
    § A "Percent Correction" Formula for Evaluation of Mixing Studies

    For PT mixing studies, a correction above 75% indicated factor deficiency, a correction below 70% indicated circulating anticoagulant, and 70% to 75% was borderline.

    “For PT mixing studies, more than 75% correction suggested the presence of a factor deficiency, less than 70% correction suggested the presence of a circulating anticoagulant, and 70% to 75% correction was considered a borderline result.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Annesley TM. Predictive value theory. In: McClatchey KD, ed. Clinical Laboratory Medicine. Baltimore, MD: Williams &amp; Wilkins; 1994:92-95.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The plasma samples were assigned to factor deficiency, circulating anticoagulant, or indeterminate groups using follow-up results and available sample information.

    “The plasma samples were classified into 3 groups representing a factor deficiency, circulating anticoagulant, or indeterminate, based on the follow-up results and available information about the samples.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The PT 4:1 mix separated factor deficiency from anticoagulant better than the PT 1:1 mix, requiring only one cutoff value instead of two.

    “In addition, as in the aPTT 4:1 mix, the PT 4:1 mix had a better separation of samples with factor deficiency from samples with anticoagulant.Only 1 cutoff value was needed in the PT 4:1 mix compared with 2 cutoff values in the PT 1:1 mix procedure for the same reason described for the aPTT 4:1 mix.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Brandt et al. also found less than satisfactory results when evaluating the three definitions of correction.

    “Brandt et al, 3 in their evaluation of these 3 definitions of correction, also showed less than satisfactory results.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Kaczor DA, Bickford NN, Triplett DA. Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing. Am J Clin Pathol. 1991;95:408-411. source

  • Probably not a substantial claim: may not pass S1 (asserted).

    Premisecitation
    § A "Percent Correction" Formula for Evaluation of Mixing Studies

    A 4:1 mixture of patient plasma with citrated normal plasma is more sensitive for detecting lupus anticoagulant.

    “Because it has been suggested a 4:1 mix of PP with CNP is more sensitive for the detection of a lupus anticoagulant, 2 we incorporated a 4:1 mix of PP with CNP into the study.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Chang S, Tillema V. Mixing study procedure changes. Laboratory News Update Marshfield Laboratories. March 8, 1994;17(3):1-7.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Kaczor et al. suggested that the 4:1 mix might be more sensitive for detecting lupus anticoagulant.

    “Kaczor et al 2 suggested that the 4:1 mix of PP with CNP might be more sensitive for detecting a lupus anticoagulant”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Chang S, Tillema V. Mixing study procedure changes. Laboratory News Update Marshfield Laboratories. March 8, 1994;17(3):1-7.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationown data

    Although incubated aPTT 4:1 testing had better sensitivity and specificity than immediate testing, the two procedures were complementary for interpreting mixing study results.

    “Although the percent correction of the aPTT 4:1 mix testing after incubation seemed to have better sensitivity and specificity for detecting anticoagulant and factor deficiency than that of the aPTT 4:1 mix with immediate testing, both incubated and immediate testing procedures were complementary to each other for interpretation of mixing study results ❚Table 10❚.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    No incubation study of PT was performed.

    “No incubation study of PT was performed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    This confirmed the impression of overcorrection in mixing studies, resulting in frequent misclassification of lupus anticoagulant samples as factor deficiency.

    “thus confirming our impression of overcorrection in the mixing studies resulting in frequent misclassification of samples with lupus anticoagulant as samples with factor deficiency.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    There was better separation of percent correction of anticoagulant from factor deficiency in the 4:1 mix; one cutoff was sufficient, while the 1:1 mix required two cutoffs due to overlapping borderline values.

    “In addition, there was a better separation of percent correction of anticoagulant from that of factor deficiency in the 4:1 mix procedure, ie, 1 cutoff value was reasonably sufficient in classifying the anticoagulant and factor deficient groups, while the 1:1 mix procedure required 2 cutoff values owing to more overlapping borderline percent correction values between the anticoagulant group and”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Annesley TM. Predictive value theory. In: McClatchey KD, ed. Clinical Laboratory Medicine. Baltimore, MD: Williams &amp; Wilkins; 1994:92-95.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Brandt et al. found that the 4:1 mix was ineffective for correcting the aPTT of the mixture and might misclassify factor deficiency as anticoagulant.

    “while Brandt et al 3 found that the 4:1 mix was ineffective for correcting the aPTT of the mixture and that it might misclassify samples with factor deficiency as anticoagulant.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Kaczor DA, Bickford NN, Triplett DA. Evaluation of different mixing study reagents and dilution effect in lupus anticoagulant testing. Am J Clin Pathol. 1991;95:408-411. source

  • May combine two claims.

    Premisecitation
    § A "Percent Correction" Formula for Evaluation of Mixing Studies

    For aPTT mixing studies, a correction above 70% indicated factor deficiency, a correction below 58% indicated circulating anticoagulant, and 58% to 70% was borderline.

    “For aPTT mixing studies, more than 70% correction suggested the presence of a factor deficiency, less than 58% correction suggested the presence of a circulating anticoagulant, and a 58% to 70% correction was considered a borderline result.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [1] Annesley TM. Predictive value theory. In: McClatchey KD, ed. Clinical Laboratory Medicine. Baltimore, MD: Williams &amp; Wilkins; 1994:92-95.

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

29 of 29

  • The paper relies on this without support.

    The follow-up laboratory results and available information used to classify samples correctly identify whether a sample has a factor deficiency or a circulating anticoagulant.

    “The plasma samples were classified into 3 groups representing a factor deficiency, circulating anticoagulant, or indeterminate, based on the follow-up results and available information about the samples.”

  • The paper relies on this without support.

    The group classification used as the reference standard correctly identifies factor deficiency versus anticoagulant status.

    “For a description of the groups, see Table 1.”
    “Group 1, factor deficiency (n = 24); group 2, indeterminate (n = 1); group 3, anticoagulant (n = 5).”
2 of 2

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Factor V percentage and decimal equivalent disagree

    Minor

    A factor V activity of 101% is 1.01 as a decimal fraction, not the reported 10.1.

    Reported 10.1 · recomputed 1.01

  • Case 24 has two different aPTT values

    Minor

    Table 1 reports an aPTT of 72.2 seconds for case 24, while Table 3 reports 77.2 seconds for the same case.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Chang S, Tillema V. Mixing study procedure changes. Laboratory News Update Marshfield Laboratories. March 8, 1994;17(3):1-7.
  2. Kasper CK. Laboratory tests for factor VIII inhibitors, their variation, significance, and interpretation. Blood Coagul Fibrinolysis. 1991;2(suppl 1):7-10.

Cited by

Sorted by citations

Related

Authors
Chang, S.-H., Tillema, V., & Scherr, D.
Affiliations
Marshfield Clinic (US)
Venue
American Journal of Clinical Pathology
Publisher
Oxford University Press (OUP)
Published
2002-01
Volume
117
Issue
1
Pages
62-73
ISSN
  • 0002-9173 (ISSN-L)
  • 1943-7722
DOI
10.1309/rrek-8l6m-d2kc-hwlh
OpenAlex
W2135696880
Cited by
67
References
10
Citations by year
2026: 3 · 2025: 3 · 2024: 4 · 2023: 4 · 2022: 4 · 2021: 2 · 2020: 4 · 2019: 6 · 2018: 5 · 2017: 2 · 2016: 4 · 2015: 3 · 2014: 3 · 2013: 3 · 2012: 5
FWCI
0.72
Type
journal article
Language
en
Open access
Locations
  • American Journal of Clinical Pathology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Hematology › Blood Coagulation and Thrombosis Mechanisms
  • Health Sciences › Medicine › Physiology › Clinical Laboratory Practices and Quality Control
  • Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Blood properties and coagulation
Keywords
mixing studies, activated partial thromboplastin time, prothrombin time, factor deficiency, plasma mixtures, incubation, sensitivity and specificity
MeSH terms
Citrates, Humans, Partial Thromboplastin Time, Prothrombin Time, Sensitivity and Specificity

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