Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT04688463 |
| Other study ID # |
H2003:104 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
January 1, 2000 |
| Est. completion date |
June 15, 2006 |
Study information
| Verified date |
December 2020 |
| Source |
University of Manitoba |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
In this retrospective observational case study, the investigators review the clinical
experience with pressure-pain algometry in children with suspected appendicitis. The
investigators hypothesized that algometry can discriminate children with appendicitis from
children without appendicitis and aimed to determine the diagnostic accuracy of algometry,
compared to ultrasound imaging and clinical assessment.
Description:
As a retrospective cohort study, participants include all children referred with abdominal
pain from January 2000 to June 2006 to one surgeon (R.P.) on the pediatric general surgery
service at the Health Sciences Centre (HSC)-Children's Hospital in Winnipeg. The
HSC-Children's Hospital is the only pediatric surgery centre within a radius of 600 km. All
included participants have had acute abdominal pain ≤ 7 days, and suspected appendicitis
based on standard history and physical exam. Standard appendicitis treatments were used:
analgesia, antibiotics, operation. The Research Ethics Board of the University of Manitoba
approved the study and reporting of the findings (H2003:104).
The investigators use standard clinical, laboratory, diagnostic imaging procedures for
appendicitis diagnosis. The final diagnosis is defined by:
- pathology report indicating transmural inflammation, or
- from the surgeon's report when pathology was unavailable, or
- by discharge diagnosis in non-operated patients.
Appendix rupture is defined by the presence of pus and full-thickness perforation of the
appendix wall or abscess formation at operation or on pathology examination. The appendix
condition is classified as normal, non-perforated or perforated; all other pathologies at
operation are recorded. Treatments, complications and morbidity are tabulated.
Clinical Measures
All patient demographics, clinical presentation details, and results of laboratory testing
(WBC) are collated. From this, the components of the Alvarado and Samuel pediatric
appendicitis scores (PAS) are calculated retrospectively for comparison purposes and not used
in patient management. Time intervals are calculated from the date and time entries in the
clinical record. Results of diagnostic abdominal imaging (U/S, CT, plain x-rays) are based on
recorded verbal or, if available, official written reports at the time of patient management
decision. Equivocal imaging results are deemed negative. The reasons why algometry was not
done are tabulated and the number of patients who reached or exceeded the maximum algometer
readout (≥4 kg)
Algometry Device and Procedure:
The principal investigator (PI) designed and produced in 1983 a simple, lightweight,
aluminum-Teflon®, pocket-size, calibrated spring-gauge algometer, similar to a tire gauge,
that was used for all measurements. The PI used this routinely in his clinical work.
Children were first familiarized with the algometer and allowed to hold and play with it. The
device head was then depressed with increasing force to the child's unencumbered mid-forearm
to simulate the abdominal examination and algometry procedure. Children were instructed to
indicate with their preferred 'signal' (e.g. 'now', 'ow!', or squeezing the examiner's
fingers) when the sensation of pressure changed to a sensation of discomfort or pain.
Pressure-pain threshold (PPT) is defined as the minimum force (in kilograms) applied via the
algometer to produce discomfort. Lower PPT readings imply greater tenderness. All
measurements were obtained and recorded by the Principal Investigator. Algometry was a
standard tool used by the PI in all clinical practice.
Single mid-forearm 'pressure-pain threshold algometry' (PPTA) measurements are used as the
patient's background, 'global', non-abdominal discomfort/pain threshold. This was then
followed by single PPTA measurements from the centre of each four abdominal quadrants in the
following sequence: left lower quadrant, left upper quadrant, right upper quadrant and right
lower quadrant. The lower quadrant centre was defined midway between the umbilicus and
anterior iliac spines. The upper quadrant centre was defined midway between the umbilicus and
mid-costal margins. Algometer depressing velocity (rate) mimicked normal, heuristic palpation
velocity (i.e. approximately 1 kg./sec (0.241 kg/cm2/sec or 23.6 kilopascal/sec). From the 5
sites, the investigators define 7 pressure-pain threshold algometric measurements of interest
(forearm, left lower quadrant, left upper quadrant, right upper quadrant and right lower
quadrant, lowest reading, average reading).
Additional algometry 'mapping' is done when the most tender site apparent on qualitative
palpation was outside the standard four abdominal quadrants e.g. suprapubic or flank
tenderness. If the algometry measurements and qualitative assessment agreed, patients are
classified as 'concordant' versus 'discordant' when no agreement. For purposes of analysis,
'discordant' patients are included with the non-mapped group. The site of these maximal
abdominal wall tenderness measurements are then correlated with the location of the inflamed
appendix found at operation.
The primary analysis is with baseline algometry readings or the final of serial readings. The
algometry readings of non-appendicitis appendectomy patients are grouped with
non-appendicitis patients.
When available and appropriate, algometry measures are repeated during the period of
diagnostic observation to determine if serial PPTA 'mirrored' the patient's clinical course.
From these algometry measures the following ratios are determined:
- Abdominal tenderness localizing ratio (ATLR), calculated as the ratio of abdominal
tenderness between the least tender (highest PPT) and most tender (or RLQ) quadrants. A
higher ATLR indicates a greater degree of tenderness localization within the abdomen;
lower ATLR indicates more diffuse tenderness.
- Global abdominal tenderness localizing ratio (GTLR), calculated as the ratio of the
forearm and most tender (or RLQ) quadrant's (lowest PPT) reading. Higher GTLR indicates
a greater degree of tenderness localized to the abdomen relative to the patient's global
discomfort/pain threshold. Patients thus serve as their own tenderness control.
For analysis of correlation with clinical variables, the Pearson correlation coefficient R2,
are calculated between the 7 PPTA's and age, weight (expressed as a percentile), and duration
of symptoms, stratified by gender.
To assess the discriminatory power and predictive values of algometry, we randomly split the
data into derivation and validation groups, stratify to gender and final diagnosis of
appendicitis. Receiver operating characteristic (ROC) analysis is then performed to identify
the area under the curve (AUC), sensitivity, specificity, positive and negative predictive
values (PPV and NPV) of algometry. The diagnostic accuracy of algometry is compared to
ultrasound assessment and clinical diagnosis, again stratified to gender. GraphPad™ is used
for all the statistical analysis.
