The purpose of the study was to determine whether,
through the use of existing electronic laboratory and
clinical care databases, it is possible to capture the
majority of reportable disease cases, and remove the
burden of case finding from the commands through
NDRS. Establishment of a more efficient reporting
system was proposed to provide more timely disease
reporting and aid in active disease surveillance.
Reporting allows for the collection of statistics that
show how often disease occurs, which helps
researchers identify disease trends and track disease
outbreaks. U.S. Navy has a modified list of reportable
medical events to accommodate for deployment limiting functions. Reports on all reportable events are
submitted to the Naval Disease Reporting System
(NDRS). Medical event surveillance is particularly
important in the military populations where medical
events can have mission-degrading implications and
affect troop strength.
Chlamydia cases were identified in the passive reporting system (NDRS), laboratory results (HL7) and
ambulatory case diagnoses (SADR). The matching
process evaluated the consistency between three independent systems, and determined whether all cases
reported in NDRS had HL7 and/or SADR records.
The investigator evaluated cases reported at Camp
Lejeune for Navy and Marine Corps active duty
members between January 1, 2006 and December 31,
2006. The Capture – Recapture statistical method
was used to estimate the total number of cases not
captured by any of the databases, therefore estimating
the overall case load burden.

A total of 583 Chlamydia cases were captured in the
databases. Of the 583 cases, 431 (73.9%) were captured using electronic databases (HL7, SADR). Seventy-six cases were estimated using the CaptureRecapture method. Overall, 659 total Chlamydia
cases were estimated at Camp Lejeune. Of the 659
total existing cases, 88.5% of the cases were captured
using the alignment of the three data sources and
65.4% were captured using only the electronic laboratory results and provider visit data.
HL7 Yes No Yes No
SADR Yes Yes No No
Yes 89 89 110 152
No 22 59 62 76
Yes: Case Captured; No: Case not captured
Figure 1 – Capture Recapture results: Number of cases captured by
one or more data sources and the estimated number of cases omitted by all systems.
The analysis showed positive indication for using the
Capture – Recapture method to establish estimates of
Chlamydia case burden at Camp Lejeune. The analysis indicated that it was possible to provide an estimated number of cases missing from all three independent data sources.
Additionally, when using positive lab results and
ambulatory care records only, the method estimated
the number of cases relatively closely to an estimate
using all three databases. The method may be useful
in the estimation of case burden at a command or
service-wide, given the ability to determine denominator values. This capability will enable health care
providers to make decisions based on burden of disease and the potential impact it may have on troop
strength and readiness.