FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2155662364> ?p ?o ?g. }

• W2155662364 endingPage "386" @default.
• W2155662364 startingPage "385" @default.
• W2155662364 abstract "Serial duplex scanning has become almost exclusively used to determine rates of restenosis after carotid endarterectomy and the progression of stenosis in unoperated carotid arteries. I have become increasingly concerned that the lack of precision of duplex scans (possibly coupled with intra-observer variability) results in an overestimation of the rates of progression of carotid stenosis when analyzed with actuarial techniques, such as the Kaplan-Meier method. The precision, not accuracy, of an instrument is the variability of repeated measurements of the same subject by the same observer. When sharp cutoff velocity values or velocity ratios are used to separate ranges of degree of carotid stenosis, such as <50% from ≥50%, forward survival analysis of sequential measurements can result in an erroneous rate of progression as the result of duplex scan imprecision. For example, in a recent publication, the calculated annualized rate of progression of carotid stenosis was 9.3% per year for 7 years.1Muluk SC Muluk VS Sugimoto H Rhee RY Trachtenberg J Steed DL et al.Progression of asymptomatic carotid stenosis: a natural history study in 1004 patients.J Vasc Surg. 1999; 29: 208-216Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar The authors report the reproducibility of duplex scan results for the same level of stenosis to be 92% for 48 carotid arteries studied within 1 month. This means that four of the 48 had a different finding and perhaps half or 4% had a higher or progression value. How much of the 9.3% per year was caused by lack of precision? A similar recent analysis indicated a 5.3% per year carotid artery stenosis progression rate.2Rockman CB Riles TS Lamparello PJ Giangola G Adelman MA Stone D et al.Natural history and management of the asymptomatic, moderately stenotic internal carotid artery.J Vasc Surg. 1997; 25: 423-431Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar Unfortunately, few studies report the precision of the duplex scanning equipment used or the intra-observer variability. I am unaware of either recognition or of attempts to prevent or correct for imprecision when applying this type data to a survival analysis. For 81 unoperated internal carotid arteries measured within 8 weeks by the same technician with an Ultra Mark 9 scanner (ATL, Bothell, Wash), I found a mean absolute difference between two peak systolic velocity (PSV) measurements of 17.5 cm/s and a mean absolute percent difference of 15.1% (range, 45 to 281 cm/s; mean, 123 cm/s). This is similar to a recently reported intra-observer difference of 13.6% for PSV in 20 carotid arteries.3Ranke C Creutiz A Becker H Trappe H-J. Standardization of carotid ultrasound.Stroke. 1999; 30: 402-406Crossref PubMed Scopus (51) Google Scholar Linear regression of my data for the standard deviation (SD) of the difference in two PSV measurements versus PSV gives a SD of 9.0 ± 0.12 PSV cm/s. For example, this regression equation predicts that a PSV of 130 cm/s has a SD of 24.6 cm/s and a 95% confidence interval of 81 to 179 cm/s for the next measurement. If 150 cm/s is used as a cutoff between <50% stenosis and ≥50% stenosis, there is an 18% chance that the next measurement will be 150 cm/s or more. I used this precision data to theoretically predict what would happen to 600 carotid arteries with actual initial PSV measurements less than 150 cm/s (101 ± 24.5 cm/s, mean ± 1 SD). All initial values were measured by the same technologist with the office machine. Subsequent measurements are predicted by Vi = Vo + SD × ND cm/s, where i = 1 is 6 months, i = 2 is 1 year, i = 3 is 2 years, i = 4 is 3 years etc, Vo is the initial actual measurement, SD is the precision standard deviation, and ND is the normal distribution. These measurements were computed with JMP version 3.1 statistical software (SAS Instituted, Cary, NC). Kaplan-Meier analysis predicts, for a SD of 15 cm/s and a cutoff of 150 cm/sec or more for progression to ≥50% stenosis, a 5.5% theoretical (erroneous) rate of progression at 6 months, a cumulative rate at 1 year of 8.2%, 10.3% at 2 years, 12.7% at 3 years, and 14.7% at 4 years. The 4-year annualized rate is 3.9% per year—all erroneous and caused by imprecision of PSV measurements. If a precision SD of 20 cm/s is used, the 4-year theoretic rate of progression is 5.5% per year. When the previous regression equation for SD is used, the 4-year rate of progression is 4.2% per year. The erroneous rates of progression decrease as more samples of the same initial velocity values are added because of the forward deletion of values that exceed the cutoff in the survival analysis. These examples of erroneous carotid stenosis progression because of lack of duplex scan precision suggest that our current information on both the rates of progression of carotid stenoses and the recurrent stenosis after endarterectomy may be high. This is a two-way street. An initial measurement is not necessarily a true one and has the same lack of precision as later ones. Initial velocity values above a cutoff value may drop below it on future testing. Forward actuarial analysis does not account for this. However, this variability may come into play in a similar way when analyzing for regression of stenosis. One way to reduce the precision SD is to take repeated measurements at the same study period, but this is probably not economically feasible. Another approach is to define the precision of the scanner and technologist and correct the Kaplan-Meier curves accordingly. I do not know how to do this, but it is probably not too difficult. The bad news is that early restenosis or progression rates are probably significantly overestimated because only two, three, or four sequential studies have been done. The good news is that the effect of imprecision dampens out the more studies are done (longer times), and late data is probably much more accurate." @default.
• W2155662364 created "2016-06-24" @default.
• W2155662364 creator A5011572051 @default.
• W2155662364 date "1999-08-01" @default.
• W2155662364 modified "2023-09-30" @default.
• W2155662364 title "Lack of precision of duplex scan velocity measurements can falsely elevate rates of progression of carotid stenosis" @default.
• W2155662364 cites W1489157723 @default.
• W2155662364 cites W1967200642 @default.
• W2155662364 cites W2152958364 @default.
• W2155662364 cites W3021697688 @default.
• W2155662364 doi "https://doi.org/10.1016/s0741-5214(99)70155-2" @default.
• W2155662364 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/10436464" @default.
• W2155662364 hasPublicationYear "1999" @default.
• W2155662364 type Work @default.
• W2155662364 sameAs 2155662364 @default.
• W2155662364 citedByCount "1" @default.
• W2155662364 crossrefType "journal-article" @default.
• W2155662364 hasAuthorship W2155662364A5011572051 @default.
• W2155662364 hasBestOaLocation W21556623641 @default.
• W2155662364 hasConcept C126322002 @default.
• W2155662364 hasConcept C126838900 @default.
• W2155662364 hasConcept C164705383 @default.
• W2155662364 hasConcept C2777910003 @default.
• W2155662364 hasConcept C2778283817 @default.
• W2155662364 hasConcept C2778583881 @default.
• W2155662364 hasConcept C2780007028 @default.
• W2155662364 hasConcept C2781038377 @default.
• W2155662364 hasConcept C2781068581 @default.
• W2155662364 hasConcept C2987047532 @default.
• W2155662364 hasConcept C54355233 @default.
• W2155662364 hasConcept C552990157 @default.
• W2155662364 hasConcept C71924100 @default.
• W2155662364 hasConcept C86803240 @default.
• W2155662364 hasConcept C99611785 @default.
• W2155662364 hasConceptScore W2155662364C126322002 @default.
• W2155662364 hasConceptScore W2155662364C126838900 @default.
• W2155662364 hasConceptScore W2155662364C164705383 @default.
• W2155662364 hasConceptScore W2155662364C2777910003 @default.
• W2155662364 hasConceptScore W2155662364C2778283817 @default.
• W2155662364 hasConceptScore W2155662364C2778583881 @default.
• W2155662364 hasConceptScore W2155662364C2780007028 @default.
• W2155662364 hasConceptScore W2155662364C2781038377 @default.
• W2155662364 hasConceptScore W2155662364C2781068581 @default.
• W2155662364 hasConceptScore W2155662364C2987047532 @default.
• W2155662364 hasConceptScore W2155662364C54355233 @default.
• W2155662364 hasConceptScore W2155662364C552990157 @default.
• W2155662364 hasConceptScore W2155662364C71924100 @default.
• W2155662364 hasConceptScore W2155662364C86803240 @default.
• W2155662364 hasConceptScore W2155662364C99611785 @default.
• W2155662364 hasIssue "2" @default.
• W2155662364 hasLocation W21556623641 @default.
• W2155662364 hasLocation W21556623642 @default.
• W2155662364 hasOpenAccess W2155662364 @default.
• W2155662364 hasPrimaryLocation W21556623641 @default.
• W2155662364 hasRelatedWork W1999414743 @default.
• W2155662364 hasRelatedWork W2038500434 @default.
• W2155662364 hasRelatedWork W2062903681 @default.
• W2155662364 hasRelatedWork W2082917209 @default.
• W2155662364 hasRelatedWork W2085743229 @default.
• W2155662364 hasRelatedWork W2130978946 @default.
• W2155662364 hasRelatedWork W2161828139 @default.
• W2155662364 hasRelatedWork W2385933126 @default.
• W2155662364 hasRelatedWork W2405789047 @default.
• W2155662364 hasRelatedWork W2406284224 @default.
• W2155662364 hasVolume "30" @default.
• W2155662364 isParatext "false" @default.
• W2155662364 isRetracted "false" @default.
• W2155662364 magId "2155662364" @default.
• W2155662364 workType "article" @default.