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Dry
mouth assessment
As with most symptoms, it is difficult to quantify dry mouth complaints
precisely and reproducibly. Investigators have used a variety
of methods including:
- Questionnaires
- Visual
analog scales (VAS)
- Simple
functional measures, such as observing if a tongue blade adheres
to the buccal mucosa or if a patient can chew and swallow a
cracker without water
The latter
methods are actually looking at surrogate markers for decreased
salivary gland function. However, as noted earlier, not all dry
mouth complaints are associated with reduced salivary gland output.
Interpretation of these methods is also very subjective and variable.
The use of simple "tests for dry mouth" such as tongue
blade adherence is inadequate for well-designed clinical trials.
As noted earlier in this chapter, salivary function can be measured
directly and is a reliable means of assessing salivary output.
It is also possible to measure oral parameters such as swallowing
time or speech fluency in an objective fashion. These may be valuable
secondary outcome measures in dry mouth studies.
Most treatments
for dry mouth, while they may increase salivary output, have utilized
improvement in oral dryness complaints as the primary outcome
measure in clinical trials. Clinical studies of secretogogues
have not examined objective parameters such as caries. This is
likely due to the relative ease with which xerostomia and other
subjective criteria can be captured, compared to the lengthy and
intensive methods necessary to quantify changes in caries rates.
Ideally, clinical trials should monitor subjective (symptomatic)
and objective improvements from treatments designed to enhance
salivary output and relieve dry mouth.
As with any
assessment technique, it is important to define exactly what is
being measured. Simple questionnaires asking for the patient's
assessment of "improvement, worsening, or no change" are useful
and allow a straightforward responder analysis (Fife
et al., 2002). However, they give no assessment of the extent
of changes and have little utility in tracking changes in symptom
severity over time.
VAS can be
used to provide a more detailed assessment of dryness and associated
symptoms (See VAS
figure). Depending on the anchors selected for the line, subjects
can be queried about different aspects of their dry mouth complaints
and alterations in symptoms can be monitored. Recently, a multiple
VAS-based questionnaire has been validated and found to correlate
with changes in salivary function and to be reliable over time
(Pai et al., 2001).
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