Journal of Rehabilitation Medicine 51-1CompleteIssue | Page 65

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G. Müller et al.
programme compared with standard care, and the ef-
fect of the programme on direct and indirect medical
costs. A further aim was to examine how the health and
economic effects correlate with back pain severity, as
measured with the Graded Chronic Pain Status (GCPS).
METHODS
Study design
This controlled multicentre study, with follow-up at 6, 12, 18
and 24 months (t0, t1, t2, t3, t4), examined the cost-effectiveness
of 6 months of multimodal back exercise (BE) compared with
standard treatment (ST). Participants in the intervention group
underwent BE in addition to the mandated health insurance
services that collectively make up ST. The control group parti-
cipants underwent only ST.
The study is categorized as a healthcare research study, since
the exercise programme is a health insurance benefit offered
by the insurer at 39 locations in the German state of Baden-
Wuerttemberg. The control group was generated from surveys
and adjusted via matching (see below). The ethics application
submitted to the University of Greifswald’s Ethics Commis-
sion (ID 33/08) was approved unconditionally on 3 June 2008.
Study participants
Prerequisites for participation in the back exercise programme
included having a prescription or a preventive referral from
the attending physician. Prescription indications include spinal
syndromes with pronounced symptoms. Contraindications are
acute back pain or back disorders, specifically, and conditions
that preclude physical exercise.
Patients with this prescription can sign up at one of 39 back
clinics in Baden-Wuerttemberg. During the period from 1 Octo-
ber 2007 to 31 March 2008, patients signing up for the exercise
programme were invited to join the study. A total of 2,444
individuals agreed in principle to take part. For each of these
participants, a statistical twin was selected from routine data (cost
and demographic data) from a reduced data sample (n = 348,000,
randomly selected) provided by the insurer (see Table I).
Individuals interested in participating in the investigation and
the selected statistical twins were invited by letter to join the
pseudonymized study. Inclusion criteria were: a GCPS status
(11) of at least grade 1, and a completed data-set of the questions
used for constructing the GCPS. For the economic evaluation, we
excluded from the study all survey subjects not covered by the
insurer for the entire duration of the study (due to cancellation
or death), since the study aimed to compare pre-intervention
medical costs during the 2 years before the start with 2 years of
post-intervention costs.
Table I. Criteria for the first round of matching
Variable Deviation
Age
Sex
Insured type
Work status
Sum of medical costs for the two
years preceding the start of the
intervention (baseline)
Medical costs related to back pain for
each of the four half years preceding
the start of the intervention
separately (baseline) ± 2 years
Match
Match
Match
± 30 %
www.medicaljournals.se/jrm
Select statistical twin with the least
sum in the absolute deviation across
all cost areas in each four half years
preceding the start of the intervention
After gathering the survey data, a second matching, which
included the GCPS (11), was performed. The second matching
was required because of significant differences among the study
groups relative to the success criteria (GCPS, back treatment
costs, work days lost due to back problems) and the standardized
differences in part also exceeded 10%. Due to the small number
of control group participants, weighted propensity score match-
ing was performed (12, 13). Matching was by age, sex, direct
medical cost categories, direct back disorder cost categories,
and work days lost due to back problems. No calliper was set.
Cost outcomes
The cost data are based on routine data supplied by the insurer.
They were pseudonymized for the study by the insurer’s in-
house information technology department. Costs are net costs
without co-payments by the insured.
The direct costs comprise all relevant cost areas, including
charges for the BE. The BE charges cover the cost of leasing
the exercise machines, exercise centre administrative costs (as
fixed by administrative regulation cost schedules) and person-
nel costs. The direct back disorder medical costs are based on
costs in the M40–M54 diagnostic index. Outpatient costs are
not included in the direct back disorder medical costs, since
pinpointing costs based on the diagnostic index codes was not
feasible in this case. Direct costs also do not include costs of
therapeutic appliances, since they are irrelevant for this disor-
der. The individual exercise costs were calculated based on the
individual number of training sessions. The cost of a training
session is the quotient of the total cost of the back exercise
programme divided by the number of training sessions.
To calculate the drug and therapeutic costs, we selected drugs
commonly prescribed for back pain (including, but not limited
to, corticoids for systemic application, antiphlogistics and anti-
rheumatics (M01A/B), muscle relaxants (M03), and health aids
(physiotherapy, massage, among others)) (Table II).
The lost productivity costs were calculated by the human ca-
pital method, based solely on the number of sick leave days and
using data produced by the Federal Institute for Occupational
Safety and Health for the years 2006–09 (14–17).
Therapeutic outcomes
For the survey, we used the GCPS (11). It contains 7 questions
on the dimensions of pain intensity and pain-induced functional
impairment in daily life, leisure, and work. For each dimension,
back pain is presented as divided into 5 grades (no pain, low pain
intensity, high pain intensity, moderate functional impairment,
and severe functional impairment).
In GCPS grades 1 (low pain intensity) and 2 (high pain inten-
sity), the back pain intensity as graded does not yet significantly
impact daily life, leisure, and work functions. The last 2 grades
are differentiated by the degree of functional impairment. Alt-
hough they are constructed exclusively according to the severity
of the functional impairment, the pain intensity dimension also
increases in both. The direct and indirect medical costs also
increase concomitantly with the GCPS (18).
Back exercise programme
The multimodal BE programme consists of dynamic strength
training of the trunk stabilizers and neck muscles, functional
gymnastics exercises, stretching and exercises in everyday
motor activity (sitting, standing, lifting loads).
Each group of 5 exercisers is supervised by a trainer. The
complete exercise programme comprises 36 training sessions