Preliminary Data Concerning Reliability and Validity

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European Journal of Psychological Assessment, Vol. 1O, 1994, lssue 2, pp. 145-151

The Development of a Spanish Questionnaire for Assessing Pain: Preliminary Data Concerning Reliability and Validity Carlos Lázaro 11 Felix Bosch 11 Rafael Torrubia 2 & Josep-Eiadi Baños 1 1

Divisió de Farmacologia and 2 Divisió de Psicologia Medica i Psiquiatria . Universidad Autónoma de Barcelona, Spain .

Keywords : McGill Pain Questionnaire, pain assessment, pain evaluation, Spanish Pain Questionnaire, MPQ-SV A Spanish list of pain descriptive words was elaborated following the methodological design of the McGill Pain Questionnaire. Sorne recommendations from other national versions were considered and integrated. In the first phase a listas wide as possible of pain descriptors was collected . In the second phase, physicians and students categorized them according to quality aspects. In the third phase, the pain descriptors were scored and ranked according to intensity by pain experts and patients. Finally, the fourth phase was designed to provide preliminary data on reliability and validity of the questionnaire. The final questionnaire, named McGill Pain Questionnaire-Spanish Version (MPQ-SVL consisted of 65 descriptors grouped in 17 subclasses.

lntroduction Pain measurement is a major concern for scientists and clinicians who want to approach the phenomena in terms of diagnosis, treatment, drug evaluation and patients follow up. Due to its subjective nature, pain remains a difficult issue to be only assessed by physical methods and the use of psychometric approaches has demonstrated its usefulness. Though physicians seem to have been trained to give more credibility to objective than subjective symptoms, a carefully constructed questionnaire can provide even higher levels of reliability and validity than many laboratory tests (Williams, 1988). With this aim Melzack & Tórgerson (1971) developed the McGill Pain Questionnaire (MPQ) which has pro ved to possess a high degree of reliability and sensitivity to be used as an universal method of assessment (McDowell & Newell, 1987). The endeavours to validate the MPQ in other languages have included severa! approaches. Direct translation has been mostly used but it presents the disadvantages of socio-cultural differences and the lack of semantic equivalents (Boureau et al., 1984; Vanderiet et al., 1987). Therefore,it seems more appropriated to create new pain questionnaires in each country following similar methodological pro-

cedures to those used in the MPQ rather than mere translations of their descriptive words. Spanish is one of the most widely spoken languages. However, a Spanish version of MPQ is still lacking as previous questionnaires were not adequately validated to test their potential usefulness in clinical settings (Lahuerta et al., 1982; Molina et al., 1984; Ruiz et al., 1990). The aim ofthe present study was to elaborate and validate a Spanish version of MPQ (MPQ-SV), following the general steps used by Melzack (Melzack & Tórgerson 1971; Melzack, 1975) and adding sorne modifications used in the creation of sorne national versions (Vanderiet et al., 1987; De Benedittis et al. , 1988; Verkes et al., 1989; Strand & Wisnes, 1991).

Methods and Results The study was performed in four different phases. The first three were devoted to the elaboration of the MPQ-SV, whereas the fourth included the process of establishing its reliability and validity. Therefore , methods and results section is divided according to this methodological procedure.

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PHASE l. Colfection of Descriptors and First Selection

Table l. Descriptors obtained in Ph ase 1 and its sources

Methods

Spanish translations French translation* Italian translation* Dictionnaire ofsynonyms Patients Patients and Spanish translations Others**

The main objective of this phase was to collect the maximum amount of words describing either pain or any associated sensation. Several potential sources of pain descriptors were included: a) Translation of the original MPQ descriptors. This was performed using a standard English-Spanish dictionary and a previous translation of MPQ to Spanish (Lah uerta et al. , 1982). For each descriptor, the available Spanish words were considered. b) Translation of a French pain questionnaire (Boureau et al., 1984) and of a Italian version of MPQ (De Benedittis et al., 1988). To avoid repetitions, only the words not included in a) were considered. e) Search of additional words describing pain by means of a Spanish synonymous dictionary. Only words not included in the a) and b) lists were considered. d) Patients descriptors. 154 patients from three hospitals, suffering from acute or chronic pain were asked to describe it. Their descriptive words were collected if they were different from a), b) ande). A fina l list with all selected descriptors was elaborated. Thereafter, a first selection was performed to eliminate bizarre or meaningless words. This screening was made by asking twenty individuals ofuniversity degree to eliminate the words they could not understand, or they would never use to describe pain. To evaluate the deleterious effects of mental fatigue , sorne archaisms and repeated words were included in the list, expecting they would display the same refusal index along all the questionnaire and thus avoiding the possibility of a "fatigue" effect in the accuracy ofthe selection method. The descriptors rejected by at least half of the participants were elirninated.

Accepted (N= 233)

Rejected (N= 110)

117 (60.9)

75 (39.1)

192

19 (73.0)

7 (27.0)

26

17 (74.0)

6 (26.0)

23

9 (34.6) 23 (92.0)

17 (65.4) 2 ( 8.0)

26 25

39 (95.1) 9 (90.0)

2 ( 4.9) 1 (10.0)

41 10

Total (N= 343)

Number in brackets indicates percentage of agreement. * See references in the text. ** In this group, descriptors that where present at the same time in the French and Italian questionnaires ancl/or in the dictionary of synonyms.

from 154 patients. This fact would reinforce the idea that patients probably only use a limited number of words to describe their pain. When evaluating the level of acceptance, the lowest refusal was observed in the patient's descriptors group. However, translation of French and Italian questionnaires also obtained a high level of acceptance.

PHASE 11. Categorization of Descriptors and Creation of the Present Pain lntensity (PPI) General Methods This phase was divided in three subsequent phases, named Phase Ha, Phase Ilb and creation of the PPI scale. Their methods and results are presented altogether in this order for a better understanding. Phase lla

Results - Methods After avoiding repetitions, a total of 343 descriptors The original names of categories and subclasses of were initially collected, being reduced to 233 after the MPQ were adequately translated by the D epartthe first selection process. Table 1 summarizes the ment of Spanish Language of the Universitat Autónoma de Barcelona to obtain the terms that more amount of descriptors collected by each source and the degree of acceptance for each of them after this accurately represent their original meaning. Acinitial screening. The majority of descriptors were cording to a modified procedure similar to that sugobtained through the MPQ translations (n=11 7), gested by Verkes et al. (1989), 107 medical students but a significant number were also provided by pavolunteered to classify each of the 233 descriptors tients (n=66). Many patients used similar descripselected in phase I in one of the subclasses. The critetors to describe their pain; this might explain why , rion to accept the inclusion in a subclass was the agreement by, at least, 65% of the participants. only 66 different descriptive words were obtained

The Development of a Spanish Questionnaire for Assessing Pain

- Results The free inclusion process was allowed to classify 53 descriptors (31 from translations and 22 from patients) into their subclasses, while an other 103 (78 from translations and 25 from patients) reached the 65% of agreement but distributed into two or three subclasses. The remaining 77 descriptors (62 from translations and 15 from patients) were classified in three or more different subclasses. Those obtained from translations were withdrawn, whereas the descriptors used by patients were considered to be further studied in Phase Ilb (see below). Several subclasses presented a high number of descriptors whereas other presented few (Fear, Evaluative) or none descriptors (Affective, Dullness, Punishment, Vegetative signs). Additionally,29 descriptors showed similar distribution frequencies for their adscription to Evaluative and Affective subclasses. This phase revealed sorne difficulties in including descriptors to sorne subclasses and also the lack of a clear cut distinction between the Evaluative and Affective subclasses. To overcome these shortcomings, the phase Ilb was initiated. Phase llb

- Methods To complete the inclusion process, 28 physicians and anaesthesiologists working in pain therapy units were asked to reclassify the 103 descriptors that, in the Phase Ila, reached the established 65% criterion only when two or three subclasses were considered together. Again , each descriptor was accepted in its subclass if at least 65% of volunteers agreed. - Results As a result of this phase, 53 descriptors (36 from translations and 17 from patients) were reclassified. The remaining were eliminated if obtained from translations (n=42) and classified in the rniscellaneous groups (see below) if they were from the patient's group. Almost all the subclasses recruited a satisfactory amount of descriptors, but Dullness and Vegetative signs included only one. No descriptors were included in the subclass Punishment and therefore it was definitively eliminated. In summary, the initial 233 descriptors were reduced to 129: 39 were obtained from patients, 67 from translations and 23 were also obtained from patients but included in threé miscellaneous subclasses named I, II and III. These subclasses were created to allocate the descriptors obtained from patients that did not reach the agreement criterion

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of 65% in Phase Ila or Ilb, as it was considered that they could express traits of difficult classification that are commonly employed to describe certain qualities of pain. Therefore, Miscellaneous I and II included those descriptors which were rated with higher frequencies for sensorial category. Miscellaneous III included those of evaluative and affective subclasses. Creation of PPI Scale

- Methods In this phase, 52 health professionals were asked to rank on a visual analogue scale (VAS), the intensity of the descriptors classified in the subclasses affective and evaluative in Phases Ila and lib. This process was performed in order to select those descriptors useful to construct the PPI scale. Mean and standard deviation were calculated for each of them. - Results According to the scores obtained, two PPI of five points were obtained. ModelA included the following descriptors: l. Leve, débil, ligero (slight) . 2. Moderado, molesto, incómodo (modera te). 3. Fuerte (severe ). 4. Extenuante, exasperante (agonizing). 5. Insoportable (unbearable). On the other hand, Model B included: l. Llevadero (bearable). 2. Incómodo, fastidioso, engorroso ( annoying) . 3. Fuerte (severe) . 4. Angustian te, muy fuerte, intenso (distressing, very severe ). 5. Inaguantable, insufrible, intolerable (unbearable). ModelA was finally selected because it included evaluative descriptors, whereas Model B used preferentially those of affective subclasses. The latter was rejected and not further used as it would be probably already represented in the affective category of the final MPQ-SV.

PHASE 111. Scoring of Pain Descriptors Methods

A total of 52 physicians, nurses and patients were asked to rank the remaining 129 descriptors distributed in 16 subclasses using the PPI scale obtained in the Phase 11. Mean and standard deviation were calculated for each of them using the rank values assigned to each descriptor in the PPI scale. After the ranking of descriptors into their subclasses was obtained, a final selection was performed to obtain a reliable questionnaire to be used in clinical setting. The optimum number of descriptors by subclass was judged to be no higher thán five. The selectíon was based in the following criteria: A) descriptors with less standard deviation were con-

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Table 2. Descriptors in their subclasses and their location according to the values obtained using the PPI MPQ

MPQ-SV

Sensory

Categoría sensorial

Temporal 1 Flickering 2 Quivering 3 Pu1sing 4Throbbing 5 Beating 6 Pounding

Temporal 1

Spatial 1 Jumping 2 Flashing 3 Shooting

Punctate pressure

1 Pricking 2 Boring 3 Drilling 4 Stabbing 5 Lancinating Incisive pressu.re 1 Sharp 2 Cutting 3 Lacerating Constrictive pressure 1 Pinching 2 Pressing 3 Gnawing 4 Cramping 5 Crushing Traction pressure 1 Tugging 2 Pulling 3 Wrenching Thermal 1 1 Hot 2 Burning 3 Scalding 4 Soaring Thermal II

1 Cool 2Cold 3 Freezing Brightness 1 Tingling 2 Itchy 3 Smarting 4 Stinging

1 A golpes 2 Contínuo

Mean± S.D.

2.63 ± 0.4 3.16 ± 0.4

Temporal /1 1 Periódico 2 Repetitivo 3 Insistente 4 Interminable Localización 1 1 Impreciso 2 Bien delimitado 3 Extenso Localización /1 1 Repartido 2 Propagado

2.38 ± 0.6 2.86 ± 0.6

Punción 1 Como un pinchazo 2 Como agujas 3 Como un clavo 4 Punzante 5 Perforante

2.09 ± 0.8 2.76 ± 0.6 3.24 ± 0.2 3.69 ± 0.6 4.25±0.2

2.21 ± 0.6 2.79 ± 0.8 3.28 ± 0.7 4.19 ± 0.5 1.99 ± 0.5 2.24± 0.3 3.06 ± 0.2

MPQ

MPQ-SV

Sensory

Categoría sensorial

Mean±S.D.

Dullness Consistencia/matidez 1 Dull 1 Pesadez 1.96 ± 0.3 2 Sore 3 Hurting 4Aching Sensory Miscellaneous Miscelanea Sensorial 1 1 Tender 1 Como hinchado 1.87 ± 0.3 2 Como un peso 2.05 ± 0.2 2Taut 3 Rasping 3 Como un flato 2.51 ± 0.7 4 Splitting 4 Como espasmos 3.07 ± 0.7 Spatial Pressure Miscelanea Sensorial /1 2.0 ±0.5 1 Spreading 1 Como latidos 2 Concentrado 2 Radiating 2.46 ± 0.5 3 Penetrating 3 Como si pasara corriente 2.65 ± 0.8 4 Calambrazos 4 Piercing 2.88 ± 0.7 Pressure Dullness Miscelanea Sensorial 1/1 1 Tight 1 Seco 2.66 ± 0.3 2Numb 2 Como martillazos 3.27 ± 0.3 3 Drawing 3 Agudo 3.46±0.4 4 Squeezing 4 Como si fuera a 5Tearing explotar 4.18 ± 0.7 Aes Miscellaneous

In cisión

1 Como si cortara 3.48 ± 0.8 2 Como una cuchillada 3.93 ± 0.4

Constricción

1 Como un pellizco 2 Como si apretara 3 Como agarrotado 4 Opresivo 5 Como si exprimiera Tracción 1 Tirantez 2 Como un tirón 3 Como si estirara 4 Como si arrancara 5 Como si desgarrara Térmicos 1 1 Calor 2 Como si quemara 3 Abrasador 4 Como hierro candente Térmicos II 1 Frialdad 2Helado Sensibilidad Tactil 1 Como si rozara 2 Como un hormigueo 3 Como si arañara 4 Como si raspara 5 Como un escozor 6 Como un picor

2.07 ± 1.1 2.35 ± 0.5 2.62 ± 0.3 2.98 ± 0.4 3.02 ± 0.6 2.11 ± 0.4 2.42 ±0.5 2.66 ± 0.4 3.73 ± 0.4 4.09 ± 0.5 2.08 ±0.5 3.24 ± 0.5 3.02±0.7 4.47 ± 0.3 2.63 ± 0.6 3.48 ± 0.7 1.52 ± 0.8 1.78 ± 0.6 1.93 ± 0.5 2.01 ± 0.4 2.35 ± 0.5 2.64± 0.9

1 Wretched 2 Blinding Affective Tensión 1 Tiring 2 Exhausting

Autonomic

Categoría emocional Tensión Emocional 1 Fastidioso 2 Preocupante 3 Angustian te 4 Exasperante 5 Que amarga la vida Signos Vegetativos 1 Nauseante

1 Sickening 2 Suffocating Fear Miedo 1 Que asusta 1 Fearful 2 Frightful 2Temible 3 Terrifying 3 Aterrador Punishment 1 Punishing 2 Grueling 3 Cruel 4 Vicious 5 Killing Affective Miscellaneous 1 Nagging 2 Nauseating 3 Agonizing 4 Dreadful 5Torturing Evaluative Categoría Valorativa 1 Annoying 1 Débil 2 Troublesome 2 Soportable 3 Miserable 3 Intenso 4 Terriblemente 4 Intense 5 Unbearable molesto

2.08 ± 0.2 2.49 ± 0.6 3.28 ± 0.5 3.75 ± 0.3 4.16 ± 0.5 2.74 ± 0.8 2.75 ± 0.7 3.58 ± 1.0 4.26 ± 1.0

1.09 ± 0.1 1.74 ± 0.3 3.42 ± 0.4 4.25 ± 0.3

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The Development of a Spanish Questionnaire for Assessing Pain

sidered first; B) when possible, the PPI of the descriptors should differ by, at least, 0.5 points into each specific subclass; and C) when these criteria did not allow the selection, descriptors obtained from patient's requests were preferred over those from translations, as it was assumed that it would refer a more real pain.

Table 3. Correlation coefficients between the rank (RPRI) and scale (S-PRI) values of the pain rating index total, sensory, affective and evaluative.

S-PRI PRI-T PRI-S PRI-A PRI-E R-PRI PRI-T

Results

Table 2 shows the final MPQ-SV with the descriptors classified in subclasses and adequately ranked with the values obtained using the PPI. Final selection reduced the number of descriptors from 129 to 65. Among these, 28 were obtained from translations, 26 from patients and 11 from the three miscellaneous groups.

PHASE IV. Reliability and Validity of the MPQ-SV Methods

Reliability and validity data were obtained from patients with clinical pain from two hospitals, 44 patients suffering from acute (postoperative) and 23 from chronic (rheumatic, neuropathic and cancer) pain. Thus, a total of 54 patients were interviewed. Data regarding their pain were obtained using the MPQ-SV, the PPI scale and a VAS were obtained. Additionally, sensitivity, i. e., ability to detect changes in pain characteristics after a therapeutic measure, was established in the subgroup of 31 women with labour pain. For this purpose, they filled the questionnaire and related measures twice, before and after an epidural block was performed. To study reliability and validity, we followed the procedure described by Vanderiet et al. (1987) to evaluate the Dutch questionnaire. Correlations (Spearman's coefficient) were calculated between the original scale values and the adjusted rank values. Correlations were also calculated among the Pain Rating Index Total (PRI-T), the sum of the scores of all the selected descriptions and its component parts: the Pain Rating Index Sensory (PRIS), Affective (PRI-A) and Evaluative (PRI-E). Correlations were finally calculated with the Number of Words Chosen (NWC), the PPI and the VAS. The data collected before and after an epidural anaesthetic block for labour pain were used to calculate the difference of scores (pretreatment minus posttreatment scores) of the PRI and the PPI. As previously explained, the sensitivity of the MPQ-SV for treatment effects was evaluated by performing a paired t-test.

0.93 (0.95)

PRI-S

0.93 (0.94)

PRI-A

0.89 (0.92)

PRI-E

0.98 (0.93)

In brackets, values described in the original description of MPQ (Melzack, 1975). PRI-T: Pain Rating Index (Total), PRI-A: Pain Rating Index (Affective), PRI-E: Pain Rating Index (Evaluative), PRI-S: Pain R ating Index (Sensorial) . Results

Table 3 shows the correlations between the original scale values and the adjusted rank values. All of them exhibited a high degree of correlation, ranging from 0.89 to 0.98. These correlation coefficients were comparable to the described when developing the original MPQ (Melzack, 1975), the differences observed being no higher than 0.05 units. Table 4 summarizes the correlations between the PRI-T and its component parts. Only the correlation between PRI-T and PRI-S was higher than 0,90 and the correlations of our study were also similar to those obtained by Melzack (1975) , as shows the Table 4. In fact, no difference higher than 0.2 units was observed in all correlations calculated when both studies were compared. Table 4. Correlation coefficients between the rank values of pain rating index, the present pain intensity scores and number of words chosen.

PRI-T PRI-S PRI-A PRI-E PPI PRI-S PRI-A PRI-E PPI NWC

0.95 (0.87) 0.67 (0.70) 0.62 (0.49) 0.54 (0.42) 0.77 (0.89)

0.43 (0.41) 0.45 (0.27) 0.43 (0.29) 0.76

0.59 (0.42) 0.49 (0.42) 0.48

0.57 (0.49) 0.35

0.35 (0.32)

In brackets, values described in the original description of MPQ (Melzack, 1975). PRI: Pain Rating Index, PPI: Present pain intensity, NWC: Number of words chosen, PRI-T: Pain Rating Index (Total), PRI-A: Pain Rating Index (Affective), PRI-E: Pain Rating Index (Evaluative), PRI-S: Pain Rating Index (Sensorial).

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Table 5. Correlations based on the difference score (pretreatment score minus posttreatment score) of the pain rating index, the present pain intensity and visual analogue scale.

PPI VAS

PRI-T

PRI-S

PRI-A

PRI-E

0.83 (0.94) 0.82

0.80 (0.90) 0.78

0.71 (0.82) 0.74

0.81 (0.96) 0.81

In brackets, values described in the original description of MPQ (Melzack, 1975) Number of patients: MPQ = 248, MPQ-SV = 31. PPI: Present pain intensity, VAS: Visual analogue scale, PRI-T: Pain Rating lndex (Total), PRI-A: Pain Rating Index (Affective), PRI-E: Pain Rating lndex (Evaluative), PRI-S: Pain Rating lndex (Sensorial).

To consider whether the differences in PRI and PPI scores correlated better than their original values (Melzack, 1975; Vanderiet et al., 1987), we calculated the correlation coefficient between them. Table 5 shows that higher values were now obtained (0.71 - 0.83), although they were slightly smaller than the obtained by Melzack (1975) (0.82- 0.96). A correlation with values of VAS was also calculated showing coefficients very similar to those obtained with PPI (Table 5). To evaluate the initial validity of the questionnaire, we checked the sensitivity of the MPQ-SV to detect changes after analgesic treatment. Table 6 shows that all difference scores were statistically significant, as scores decreased after treatment. Table 6. Sensitivity analysis performed on the difference score (pretreatment minus posttreatment) on the pain rating index, the present pain intensity and the number of words chosen (n = 31).

PRI-T PRI-S PRI-A PRI-E PPI NWC

ADS

SD

t-value Signi ficance (p)

31.29 23.87 3.93 3.12 3.61 12.93

1.27 1.03 0.27 0.13 0.13 0.28

24.54 23.03 14.57 22.82 26.45 45.29