The study was conducted at the Phototherapy Clinic
of "Shmuel Harofe" Geriatric Medical Center from
October 1989 to March 1990.
Subjects: We recruited
50 patients (34 women, 16 men) aged 55 to 86 years
(mean age 68 8.7 years). All patients fulfilled
criteria for the diagnosis of DOA of both knees and
had suffered from pain for at least 3 months. All
patients signed an informed consent approving the
procedures applied in this study. The following
patients were excluded: patients with cancer, any
acute disease, uncontrolled diabetes mellitus,
untreated hypertension, neurological deficits (motor
or sensory), psychotic disorders, dementia, mental
retardation or other organic mental disorders.
Patients already on treatment for more than 6 weeks
continued their medication with drugs that could
interfere with the intensity of pain, such as
antidepressants, minor tranquilizers, or analgesics.
Study Design: Three
types of light emitters were used: red, infrared,
and placebo. The placebo emitter was like the
infrared emitter in appearance bit did not emit
light. The study was conducted in double-blinded
fashion for the infrared and placebo emitters but
not for the red emitter where light is visible and
produces a different treatment experience. All light
emitters were supplied by AMCOR LTD. (Table 1). The
emitters used in the double-blinded groups had code
numbers, and their characteristics were unknown to
the patients and medical staff. The patients were
randomly divided into red, infrared, and placebo
treatment groups.
|
TABLE 1. LIGHT EMITTERS SPECIFICATION |
| |
Red
CW |
Red
Pulse |
IR
CW |
IR
Pulse |
|
Output power (mW) |
18 |
75 |
25 |
270 |
|
Illuminated area (cm2) |
2 |
2 |
2 |
2 |
|
Power density (mW/cm2) |
8 |
34 |
11 |
122 |
|
Pulses per second |
|
100 |
|
100 |
|
Duty ratio (%) |
|
10 |
|
1 |
|
Pulse time (ms) |
|
1 |
|
0.1 |
|
Delivery energy (J/min) |
1.08 |
0.45 |
1.5 |
0.16 |
|
CW = Continuous Wave; IR = Infrared |
Pain was evaluated by Short-Form McGill Pain
Questionnaire (SF-MPQ), by Present Pain Intensity
(PPI) Questionnaire, and by Visual Analogue Scale
(VAS).15
The main component of the SF-MPQ has 15 descriptors
(11 sensory and four affective) that are scored from
0 to 3 (0 = none, 1 = mild, 2 = moderate, 3 =
severe). The data obtained provide information on
the sensory, affective, and total intensity of pain.
PPI and VAS provide indices of total intensity of
pain. PPI is scored form 0 to 5 (0 = no pain, 1 =
mild, 2 = discomforting, 3 = distressing, 4 =
horrible, 5 = excruciating). VAS is scored from 0 to
10 (0 = no pain, 10 = worst possible pain), and the
patients are requested to record the impact of pain
on this scale.
Patients’ functional ability was measured by the
Disability Index Questionnaire (DIQ).16
DIQ has nine general components (dressing and
grooming, arising, walking, hygiene, reach, grip,
outside activity, and sex activity), each of which
has one or more specifications. Each question is
scored from 0 to 3 (0 = without difficulty, 1 = with
difficulty, 2 = with some help from another person,
3 = unable to do). The index is calculated by adding
the scores of the components and dividing it by the
total number of components answered.
Treatment: The
treatment was applied at both sides of the knee for
15 minutes twice a day. Every treatment was composed
of 7.5 minutes of continuous wave (CW) application
and 7.5 minutes of pulse treatment. Total delivered
energy was similar for the red emitters (10.3
joules) and the infrared emitters (11.1 joules).
Energy density calculated as J/cm2 was
5.1 for the red emitters and 5.6 for the infrared
emitters.
At follow-up in May 1991 we summed up the interval
that elapsed from the end of the study until the
patient’s request to be retreated because of pain.
Data Analysis:
Baseline characteristics of the groups were compared
by one-way analysis of variance and unpaired t
test. The data obtained from DIQ, SF-MPQ, PPI,
and VAS before treatment, and the data obtained from
the same tests after treatment, were evaluated using
paired t tests. |
