Faculdade de Medicina da Universidade do Porto
(Medicine College of Oporto University)
Introduction to Medicine
Prevalence of chronic pain in
adult general population within
Oporto area
Workgroup by class 17
School Year 2006/ 2007
Faculdade de Medicina da Universidade do Porto
(Faculty of Medicine of Oporto )
Introduction to Medicine
1st School Year
Annual assignment
Subject’s Main Teacher: Altamiro Costa Pereira, MD, PhD
Instructor: Luis Azevedo, MD
Introduction
1. Research question
What is chronic pain (CP) prevalence in adult general population within
Oporto area?
1.1 Context of question
Chronic
pain
is
Tulder (1995, referred
a
contemporaneous
by Chrubasik et al
issue. According
[1])
to
we can even say,
that “Chronic pain is a burden to individuals and a challenge to
society.”.
Therefore, this study expects to be an interesting and attractive
way of learning about this matter.
[1] Chrubasik S, Junck H, Zappe HA, Stutzke O. European Journal of Anaesthesiology. 1998.
Introduction
First challenge seems to be the very definition of chronic pain.
Literature studied shows that there is no established pattern about this
subject.
Basically, International Association for the Study of Pain (IASP)
defines pain as:
[3]
“ An unpleasant sensory and emotional experience associated with actual or
potential tissue damage, or described in terms of such damage.”
Which defines the subjective character of the definition to any kind of pain.
[3] Harstall C, Ospina M. Pain Clinical Updates. 2003. Available from: http://www.iasp-pain.org/terms-p.html#Pain.
Introduction
Murray
[2]
says that:
“Chronic pain is an important and social problem for three major
reasons.
It is distressing to patients, as it alters their lives and
sometimes their employment, and it responds poorly to treatment.
Chronic pain is a common condition that has huge financial costs to
society. Finally, despites its frequency and large costs, it is difficult to
understand and manage, and eventually becomes a source of stress and
misunderstanding to all concerned”.
[2] Murray OC. Available from : http://www.wcb.ns.ca/chronicpain.pdf.
Introduction
And more precisely,
“The International
provides
a
widely
Association for
used definition
duration and “appropriateness”.
the Study of Pain (IASP)
of CP that takes into account
IASP defines CP as pain
without
apparent biological value that has persisted beyond the normal
tissue healing time (usually taken to be 3 months).”
[3]
Thus, accordingly to the definition of IASP and studied literature
of CP, we can accept in practice for this study an endurance further than
3 months.
[3] Harstall C, Ospina M. Pain Clinical Updates. 2003. Available from: http://www.iasp-pain.org/terms-p.html#Pain.
Introduction
2. Primary goal
Estimate
the
period
prevalence of chronic
pain
in adult
general population within Oporto area.
Specifically, for this study, it will be considered as a primary
objective the estimate of the period prevalence of CP in general adult
population of Oporto1 area. This is, the prevalence of CP in the last year
(referring to the date of the answer).
1
This region
Azeméis, Ovar,
includes the following councils: Arouca, Espinho, Gondomar, Maia, Matosinhos, Oliveira de
Paredes, Porto,
Póvoa de Varzim, Sta. Maria da Feira, Sto. Tirso, São João da Madeira, Trofa, Vale
de Cambra, Valongo, Vila do Conde and Vila Nova de Gaia. Defined, using the call list: Oporto area and South of the
Douro.
[3] Harstall C, Ospina M. Pain Clinical Updates. 2003. Available from: http://www.iasp-pain.org/terms-p.html#Pain.
Introduction
2.1. Context of primary goal
“Yet access to reliable data on prevalence – the proportion of a
defined population that has CP at some specified time – is an important
prerequisite for efficient planning of health services.
Understanding
factors
that
underlie variation in prevalence
estimates of CP can advance our understanding of its public health
impact.” [3]
Introduction
3. Secondary goals
3.1. Estimate prevalence of CP relatively to sex;
3.2. Relate prevalence of chronic pain with age;
3.3. Estimate location of pain;
3.4. Find potential causes/origins of pain;
3.5. Scale grade of pain (without loss due to subjectivity);
3.6. Register in which ways chronic pain interferes the subject’s
familiar and social life;
3.7. Estimate the number of individuals with clinical confirmation
of chronic pain;
Methods
1. Study design
“Cross sectional studies:
These
are primarily used to determine prevalence.
Prevalence
equals the number of cases in a population at a given point in time. All
the measurements on each person are made at one point in time.”
[4]
Like Newman [et al] [5] says, in a cross-sectional study the
investigator makes all measurements on a single occasion, there is
no follow up period. And in fact, the cross sectional design is the only
one that gives the prevalence of a disease or risk factor.
[4] Mann, CJ. Emergency Medicine Journal. 2003. Available from: emj.bmjjournals.com.
[5] Newman TB, Warren SB, Steven RC, Stephen BH. In Designing Clinical Research.
Methods
Objective
Common design
Prevalence
Cross sectional
Incidence
Cohort
Cause (in order of
reliability)
Cohort, case-control, cross sectional
Prognosis
Cohort
Treatment effect
Controlled trial
Table 1: adapted of
[4]
[4] Mann, CJ. Emergency Medicine Journal. 2003. Available from: emj.bmjjournals.com.
Methods
As key points we would like to distinguish:
“The most important advantage of cross sectional studies is that in
general they are quick and cheap. As there is no follow up, less resources
are required to run the study.
Cross sectional studies are the best way to determine prevalence
and are useful at identifying associations that can then be more rigorously
studied using a cohort study or randomized controlled study.
The
most
important
problem
with
this
type
differentiating cause and effect from simple association.”
of
study
is
[4]
[4] Mann, CJ. Emergency Medicine Journal. 2003. Available from: emj.bmjjournals.com.
Methods
2. Sample dimension
Sample
dimension,
will
be
determine
in
function
of
the
appropriate calculation of algorithm to permit describe confidence intervals
for proportions with error margin of 7 %, for a level of confidence of 95%.
Allowing for an anticipated failure to respond of about 50%, the
sample size defined includes 400 individuals.
Methods
3. Data collection
In order to achieve answers for primary and secondary goals,
data collection of this study will describe the followings steps:
- Send on a postal questionnaire to 400 individuals, residents within
Oporto area, registered in Phone book “Região do Porto e Sul do
Douro;
- The questionnaires, have been sent in 30th March of 2007;
- To improve response rates, it will be send a second correspondence
to the 400 individuals after 2 weeks: 16th April of 2007.
Methods
4. Sample selection
According to precedent references it will be used the Phone
book “Região do Porto e Sul do Douro”. Specifically, relation with this
“data register”, it will be important to point some practical aspects:
- It is a register of simple use and easy access;
- However, the sample is reduced to the residents within Oporto area,
registered in Phone book “Região do Porto e Sul do Douro. The
signatures can be on behalf of an already deceased individual or a
person that has changed of habitation;
Methods
On the other hand, the questionnaire is not applicable to illiterate
individuals, or those with difficult to understanding questions.
Therefore, it is not an immediate method, once it is dependent of
the fulfillment of the services: CTT.
Methods
SuperCool Random Number Generator
This
software
facilitates
our
sampling
selection:
Sample
randomized in groups.
Through the indication of the behind described interval, this
software will randomly generate the numbers corresponding to page,
column and line; where we will find the address of the participants.
It guarantees a randomly choice (on age, sex and other social-
demographic aspects). But, in the other hand, the software does not
guarantee a valid address with the combination page/ column / line. To
resolve this limitation, it was created a Standard Operation Procedures.
Methods
4.1. Selection of participants - drawing
Random draw of:
- page: [89 , 1429] , x E |N
- column: [1 , 4] , x E |N
- line: [1 , 133] , x E |N
For the Phone book “Região do Porto e Sul do Douro”
Using the software program: SuperCool Random Number Generator 1.04
Methods
5. Pilot study
After selection of 20 addresses, using the software: SuperCool
Random Number Generator1.04, it was sent a pre-test questionnaire.
In this pre-test, we tried to improve our questionnaire, finding
some difficulties in the answers people would gave us.
Sent on 5th February 2007.
Deadline of reception: 19th February 2007.
Methods
20 Questionnaires sent
5 Returned with address unknown
1 questionnaire returned
With a very low response rate, our objectives in this pre-test haven’t
been fulfilled.
So, we started applying our questionnaire on the streets to any
person who were available to spend a couple of minutes.
Methods
Main conclusions:
We noticed that our questionnaire needed some changes:
- creation of a new question asking the sex;
- creation of a new question asking for medical conformation of
chronic pain;
- ask age instead of birth date;
- need to change some vocabulary.
Results
1. Response rate
400 Questionnaires sent
52 Returned with address unknown
62 questionnaire returned
A total of 62 questionnaires were returned after the two mailings,
which represents a response rate of 17,82%.
Results
Citizens Randomly
drawn from the
phone book
N=400
52 returned with
addresss
unknown
N=348
Returned questionnaire
N=62
Response rate:
62/348=17,82%
Participants not
in Chronic
Pain
Participants who
reported generally
having pain
Missing responses to
the question related
with having pain
N=35
N=25
N=2
Participants in
pain <3 months
duration
Participants in
pain ≥3 months
duration
Praticipants that
did not know pain’s
duration
Participants that
did not answer
(missing)
N=3
N=20
N=1
N=1
Results
2. Characteristics of the total sample
AGE
SEX
Frequency
Percent
Female
34
54.8%
Male
26
41.9%
Missing
2
3.2%
Total
62
100%
Frequency
Percent
18 - 44
21
33.9%
45 - 64
23
37.1%
>= 65
16
25.8%
Missing
2
3..2%
Total
62
100%
Minimum: 19 years
Maximum: 85 years
Results
MARITAL STATUS
Frequency
Percent
Single
14
22.6%
Separeted or divorced
4
6.5%
Married
36
58.1%
Widow
6
9.7%
Total
60*
100%
* 2 missing
Results
EDUCATIONAL STATUS
Frequency
Percent
without schooling
2
3.2%
Primary school
16
25.8%
Elementary school
5
8.3%
Secundary school
20
33.3%
University
17
28.2%
Missing
2
3.2%
Total
62
100%
Results
EMPLOYMENT STATUS
Frequency
Percent
Valid Percent
Full-time
14
22,6
23,7
Part-time
2
3,2
3,4
Housewives
9
14,5
15,3
Liberals
6
9,7
10,2
Student
8
12,9
13,6
Pensioned
2
3,2
3,4
Unemployed (looking for 1st Job)
16
25,8
27,1
Other
2
3,2
3,4
Total
59
95,2
100,0
Missing
3
4,8
Total
62
100,0
Results
3. People with Pain
We noticed 49,2% of the homes that answered to our questionnaire
reported the presence of at least one person with Chronic Pain (pain of > 3
months duration).
CI 95% for mean [36,3 ; 62,1]
Results
- The prevalence of chronic pain in our sample is 33,3% with a CI 95% [21,1
; 45,6].
Frequency
Valid
Missing
Total
Percent
Valid Percent
Cumulative
Percent
Without CP
40
64,5
66,7
66,7
With CP
(> 3 meses)
20
32,3
33,3
100,0
Total
60
96,8
100,0
2
3,2
62
100,0
Non response
Results
- Prevalence of chronic pain has higher values in female than in male,
despite the fact that their confidence intervals coincide in some values.
Sex
Statistic
0,4194
Proportion
Female
Chronic
Pain
CI 95% for
mean
Lower Bound
0,2354
Upper Bound
0,6033
0,1923
Proportion
Male
CI 95% for
mean
Lower Bound
0,0300
Upper Bound
0,3546
Results
Crosstab
Sexo
Feminino
Mas culino
Total
Count
% within Sexo
% within Dor Crónica
Count
% within Sexo
% within Dor Crónica
Count
% within Sexo
% within Dor Crónica
Dor Crónica
Com dor
Sem dor
crónica (>
crónica
3 mes es)
18
14
56,3%
43,8%
46,2%
73,7%
21
5
80,8%
19,2%
53,8%
26,3%
39
19
67,2%
32,8%
100,0%
100,0%
Total
32
100,0%
55,2%
26
100,0%
44,8%
58
100,0%
100,0%
Chi-Square Tests
Pears on Chi-Square
Continuity Correctiona
Likelihood Ratio
Fisher's Exact Test
Linear-by-Linear
Ass ociation
N of Valid Cas es
Value
3,915 b
2,881
4,048
3,848
df
1
1
1
1
Asymp. Sig.
(2-s ided)
,048
,090
,044
Exact Sig.
(2-s ided)
Exact Sig.
(1-s ided)
,056
,044
,050
58
a. Computed only for a 2x2 table
b. 0 cells (,0%) have expected count les s than 5. The minimum expected count is
8,52.
Results
- Participants have been divided into three age groups in order to help us
to understand the relation between age and CP.
Age
Statistic
0,2381
Proportion
[18-44]
CI 95% for
mean
Lower Bound
0,0394
Upper Bound
0,4368
0,2381
Proportion
Chronic
Pain
[45-64]
CI 95% for
mean
Lower Bound
0,0394
Upper Bound
0,4368
0,5333
Proportion
≥65
CI 95% for
mean
Lower Bound
0,2474
Upper Bound
0,8193
Results
- Duration of Pain – here we tried to understand the period of pain that our
participants have experienced.
5
Weighted
Average(Definition 1)
Tukey's Hinges
Duration of Pain
(months )
Duration of Pain
(months )
12,0000
10
25
Percentiles
50
12,0000
44,2500
61,0000
120,0000
48,0000
61,0000
120,0000
75
90
219,6000
95
.
Results
- Pain intensity – participants were told to describe the pain intensity using
a 0-10 scale.
Intensity
Median
Minimum
Maximum
Interquartil
Range
Maximum
6
2
10
2
Mean
6
1
10
1
- Interference in welfare – we can see that chronic pain has an interference
in people’s feelings. We used a 0-5 scale.
Median
Minimum
Maximum
Interquartile
Range
Sad/Depressed
4
0
5
2
Nervous/Ansious
4
1
5
2
Angry
3
0
5
3
Lonely/Isolated
3
0
5
4
Incapable joy life
4
0
5
2
Results
- Interference in general life – here, we used a 0-10 scale in order to
understand how chronic pain can limit the normal activity of people’s life.
Median
Minimum
Maximum
Interquartile Range
Ample capacity
6
3
10
3
Mood
6
0
10
3
Ability to walk
6
3
10
3
Normal work
7
3
10
4
Relationship with other persons
3
0
10
6
Sleep
7
0
10
6
Life Pleasure
6
0
10
5
Results
- We selected the questionnaires of the people who have pain and tried to
understand the very nature of the pain.
The pain nature
Valid
Cons tant
Variable
Periodic and regular
Periodic and irregular
Total
Frequency
3
4
6
7
20
Percent
15,0
20,0
30,0
35,0
100,0
Valid Percent
15,0
20,0
30,0
35,0
100,0
Cumulative
Percent
15,0
35,0
65,0
100,0
Results
- Pain’s location – we present here the ranking of the locations proposed to
our participants..
Disease/problem that causes pain
Frequency
Proportion
Lumbar region
12
0,6
Head and neck posterior
9
0,45
Lower Limbs anterior
7
0,35
Dorsal region
6
0,3
Upper Limbs anterior
5
0,25
Lower Limbs posterior
5
0,25
Head and neck anterior
4
0,2
Thorax anterior
4
0,2
Upper Limbs posterior
4
0,2
Abdomen anterior
3
0,15
Results
- Pain’s location
9
6
12
7
Results
- Causes / Origins of pain – Each participant could mention more than one
disease.
The main problems/diseases our participants reported were:
1. Spinal Column – 10/20 participants
2. Arthritis – 9/20 participants
3. Headaches – 4/20 participants
4. Surgical procedures – 4/20 participants
Results
- Medically confirmed pain
Medically Confirmed Pain
Valid
Mis sing
Total
Yes
No
Don't know
Total
Non res pons e
Frequency
6
12
1
19
1
20
Percent
30,0
60,0
5,0
95,0
5,0
100,0
Valid Percent
31,6
63,2
5,3
100,0
Cumulative
Percent
31,6
94,7
100,0
Results
- Professional Interference – working days lost due to pain in the last 6
months.
15 participants answered, 5 participants did not.
Descriptives
Working days
lost
Mean
95% Confidence
Interval for Mean
Median
Minimum
Maximum
Lower Bound
Upper Bound
Statis tic
8,93
-4,22
22,09
,00
0
90
Std. Error
6,134
Results
- Participants were instructed to report their medication and/or treatment.
Statistics
N
Mean
Median
Std. Deviation
Minimum
Maximum
Sum
Percentiles
Valid
Mis sing
25
50
75
Drugs
20
0
,85
1,00
,366
0
1
17
1,00
1,00
1,00
Physiotherapy
20
0
,20
,00
,410
0
1
4
,00
,00
,00
Swimming and/or
Hydrogym
20
0
,15
,00
,366
0
1
3
,00
,00
,00
Mas s ages
20
0
,00
,00
,000
0
0
0
,00
,00
,00
Osteopathy
20
0
,05
,00
,224
0
1
1
,00
,00
,00
Mus cle Distres s
20
0
,05
,00
,224
0
1
1
,00
,00
,00
Results
- We asked participants to report, using a 0-100 scale, their relief in the last
6 months with treatment.
Pain relief / Treatment success
Valid
Mis sing
Total
20
30
40
50
60
70
90
100
Total
Non
res pons e
Frequency
1
1
6
4
1
1
1
2
17
Percent
5,0
5,0
30,0
20,0
5,0
5,0
5,0
10,0
85,0
3
15,0
20
100,0
Valid Percent
5,9
5,9
35,3
23,5
5,9
5,9
5,9
11,8
100,0
Cumulative
Percent
5,9
11,8
47,1
70,6
76,5
82,4
88,2
100,0
Results
- Professional attendance – we wanted to know how many participants are
followed-up by any health professional and the most solicited ones.
Professionals
Frequency
Specialist
10
GP
9
Physiotherapist
1
Osteopath
1
Psychologist
1
Nurse
1
Conclusion / Discussion
•
According to our study, 33.3% of the respondents reported pain of ≥3
month’s duration (chronic pain);
•
The prevalence of chronic pain is higher in female than in male;
•
Most individuals described high values for their pain intensity and for
interference of pain in social life (but the results not permit us a sustainable
conclusion because is a very subjective issue);
•
Almost 25% of the study participants had experienced chronic pain for over
10 years.
Table: Comparative description of the characteristics of 13 studies on chronic pain
[3] Harstall C, Ospina M. Pain Clinical Updates. 2003. Available from: http://www.iasp-pain.org/terms-p.html#Pain.
References
[1] Chrubasik S, Junck H, Zappe HA, Stutzke O. A survey on pain complaints and health care
utilization in a German population sample. European Journal of Anaesthesiology. 1998; 15: 397408.
[2] Murray
OC. Chronic pain. [monograph on the Internet].Workers Compensation Board of Nova
Scotia. Available from : http://www.wcb.ns.ca/chronicpain.pdf.
[3] Harstall C, Ospina M. How Prevalent is Chronic Pain? Pain Clinical Updates. 2003 Jun; Vol. XI, 2.
Available from: http://www.iasp-pain.org/terms-p.html#Pain.
[4] Mann, CJ. Observational
case-control
research methods. Research design II: cohort, cross sectional, and
studies. Emergency
Medicine
Journal. 2003; 20: 54-60. Available
from:
emj.bmjjournals.com.
[5] Newman
TB, Warren
SB, Steven RC, Stephen BH. Designing
an Observational
Study: Cross-
sectional and Case-control Studies. In Designing Clinical Research. P.107.
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Acknowledgements
Subject’s Main Teacher: Altamiro Costa Pereira, MD, PhD
Instructor: Luis Azevedo, MD