title: Option-4 algorithm for Florida pocket depth probe: reduction in the variance of site-specific probeable crevice depth measurements.
abstract: Clinical periodontal measurement is plagued by many sources of error which result in aberrant values (outliers). This study sets out to compare probeable crevice depth measurements (PCD) selected by the option-4 algorithm against those recorded with a conventional double-pass method and to quantify any reduction in site-specific PCD variances. A single clinician recorded full-mouth PCD at 1 visit in 32 subjects (mean age 45.5 years) with moderately advanced chronic adult periodontitis. PCD was recorded over 2 passes at 6 sites per tooth with the Florida Pocket Depth Probes, a 3rd generation probe. The option-4 algorithm compared the 1st pass site-specific PCD value (PCD1) to the 2nd pass site-specific PCD value (PCD2) and, if the difference between these values was >1.00 mm, allowed the recording of a maximum of 2 further measurements (3rd and 4th pass measurements PCD3 and PCD4): 4 site-specific measure-meets were considered to be the maximum subject and tissue tolerance. The algorithm selected the 1st 2 measurements whose difference was < or = 1.00 mm (SPCD1 and SPCD2). If no 2 measurements had a difference < or = 1.00 mm, the examiner was required to select the 2 measurements closest to the rules of the algorithm. 4600 sites were available for analysis. 3992 sites (86.8%) required 2 recordings, 564 sites (12.3%) required 3 recordings and 44 sites (1%) required 4 recordings. Correlation coefficients for PCD1 and PCD2 and SPCD1 and SPCD2 were 0.83 and 0.96, respectively (p=0.00). Site-specific variances were calculated for PCD1 and PCD2 and SPCD1 and SPCD2. The mean of the PCD1/PCD2 site-specific variances (A) was 0.41 mm2 (range 0.00 mm2 to 33.62 mm2), whilst the mean of the SPCD1/SPCD2 variances (B) was 0.1 mm2 (range 0.00 mm2 to 2.0 mm2): the respective medians were 0.08 mm2 and 0.02 mm2. The study demonstrated high intra-examiner PCD agreement. The option-4 algorithm produced a reduction of 75.6% in the mean site-specific variance of PCD1/PCD2 (Y) (Y=[(A-B)/A]X 100) and a 75% reduction in the median site-specific variance of PCD1/PCD2.
authors.affiliation: Statistics Unit, Public Health Laboratory Service, Colindale, London, UK. harry.breen@argonet.co.uk
authors.forename: H J
authors.initials: HJ
authors.lastname: Breen
authors.forename: P
authors.initials: P
authors.lastname: Rogers
authors.forename: N W
authors.initials: NW
authors.lastname: Johnson
authors.forename: R
authors.initials: R
authors.lastname: Slaney
mesh_terms: D000328:Adult; D000465:Algorithms; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D005260:Female; D005431:Florida / Q000453:epidemiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010512:Periodontal Index; D010514:Periodontal Pocket / Q000175:diagnosis* / Q000453:epidemiology; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric