Does capture-recapture analysis provide more reliable estimates of the incidence and prevalence of leg ulcers in the community?
OBJECTIVE
To determine whether capture-recapture analysis provides more reliable estimates of the cumulative incidence and prevalence of leg ulcers in Auckland, New Zealand.


METHODS
A population-based, cross-sectional study was conducted in the Central and North Auckland health districts of New Zealand in 1998. Cases were identified through health professional referral and by self-notification. All ages and ulcer types were investigated. Both traditional and capture-recapture methods of analysis were used to estimate the cumulative incidence and prevalence of leg ulcers in the study population.


RESULTS
Four hundred and twenty-six people with current leg ulcers were identified during the 12-month study period. Using traditional methods of analysis, the annual cumulative incidence rate of leg ulcers in Auckland was 32 per 100,000, with a point prevalence of 39 per 100,000 and a period prevalence of 79 per 100,000 per year. Results from capture-recapture analysis, however, suggest an annual cumulative incidence rate of 252 per 100,000, with a point prevalence of 248 per 100,000 and a period prevalence of 530 per 100,000 per year.


CONCLUSIONS
The traditional method of calculating cumulative incidence and prevalence clearly under-estimates the frequency of leg ulcers in the Auckland region. Capture-recapture analysis provides a more reliable estimate of disease frequency, since cases that remain unidentified in the population are considered.
Walker
Natalie K
NK
Department of Medicine, University of Auckland, New Zealand. n.walker@ctru.auckland.ac.nz
Vandal
Alain C
AC
Holden
Jennifer K
JK
Rodgers
Anthony
A
Birchall
Nicholas
N
Norton
Robyn
R
Triggs
Christopher M
CM
MacMahon
Stephen
S
D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003625:Data Collection / Q000379:methods*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007871:Leg Ulcer / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009520:New Zealand / Q000453:epidemiology; D015995:Prevalence; D012107:Research Design