Anxiety Disorders 19 (2005) 893–903

Psychometric properties of the Spanish version of the Obsessive–Compulsive Inventory— Revised in a non-clinical sample Miquel A. Fullanaa,*, Miquel Tortella-Feliub, ´ scar Andio´na, Rafael Torrubiaa, Xavier Caserasa, O David Mataix-Colsc b

a Department of Psychiatry, Autonomous University of Barcelona, Catalonia, Spain Department of Psychology, University Research Institute on Health Sciences (IUNICS), University of the Balearic Islands, Majorca, Spain c Institute of Psychiatry, King’s College, London, UK

Received 8 June 2004; received in revised form 30 September 2004; accepted 25 October 2004

Abstract The psychometric properties of a Spanish version of the Obsessive–Compulsive Inventory—Revised (OCI-R) were examined in a non-clinical student sample (n = 381). A confirmatory factor analysis replicated the original six-factor structure. The total and each of the subscales of the Spanish OCI-R demonstrated moderate to good internal consistency and test-retest reliability, moderate convergent validity and good divergent validity. The Spanish version of the OCI-R retains the sound psychometric properties of the original version. # 2004 Elsevier Inc. All rights reserved. Keywords: Obsessive–compulsive disorder; Assessment; Symptom dimensions

1. Introduction Several self-report measures of obsessive–compulsive symptoms have been developed over the years (see Taylor, 1998, for a review). New self-report * Corresponding author. Tel.: +34 93 581 12 23; fax: + 34 93 581 14 35. E-mail address: [email protected] (M.A. Fullana). 0887-6185/$ – see front matter # 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.janxdis.2004.10.004

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measures have recently been developed to overcome the limitations of their predecessors, particularly their insufficient coverage of all types of symptoms. These include the Padua Inventory (Sanavio, 1988) and its subsequent revisions (e.g. the Padua Inventory—Washington State University Revision, PI-WSUR; Burns, Keortge, Formea, & Sternberger, 1996); the Vancouver Obsessional Compulsive Inventory (Thordarson et al., 2004), a revision of the widely used Maudsley Obsesional Compulsive Inventory (MOCI; Hodgson & Rachman, 1977); and the Obsessive– Compulsive Inventory (OCI; Foa, Kozak, Salkovskis, Coles, & Amir, 1998). The OCI consists of 42 items grouped in seven subscales (checking, washing, obsessing, mental neutralizing, ordering, hoarding, and doubting) measured on two 5-point Likert scales of symptom frequency and associated distress. The OCI showed sound psychometric properties in both clinical (Foa et al., 1998) and nonclinical samples (Simonds, Thorpe, & Elliott, 2000; Wu & Watson, 2003). However, since frequency and distress scales of the questionnaire seemed redundant and in order to make the administration easier, a revised and shortened version was developed, the Obsessive–Compulsive Inventory—Revised (OCI-R; Foa et al., 2002). The OCI-R consists of 18 items and provides a total score and scores on six subscales: washing, checking, ordering, obsessing, hoarding, and neutralizing. The psychometric properties of the OCI-R were examined in a sample of 215 patients with OCD, 243 patients with other anxiety disorders, and 677 nonanxious individuals (Foa et al., 2002). The OCI-R had good or excellent internal consistency, test-retest reliability, and convergent validity. It also showed a good ability to discriminate between patients with OCD and other anxious groups, with the exception of its hoarding and ordering subscales. Recently, Hajcak, Huppert, Simons, and Foa (2004) have presented data of two studies which examined the psychometric properties of the OCI-R in a college sample. Their results confirmed the six-factor structure obtained by Foa et al. (2002) and indicated adequate test-retest reliability for the full scale and subscale scores, high internal consistency, and good convergent and divergent validity. The OCI-R seems therefore a promising instrument for the assessment of both clinical and non-clinical samples. However, its psychometric properties have not been examined independently by a group of investigators that did not develop the measure or in other cultural contexts. Although prevalence rates of OCD are remarkably consistent among different cultures, some variability in symptom presentations exists, which could be related to cultural factors (Weissman et al., 1994). The replication of research across different societies requires the use of instruments that have been standardized in those cultural contexts. Furthermore, practical reasons such as having usable clinical assessment techniques or the possibility of usage in multicenter treatment trials foster the cross-cultural adaptation of assessment instruments (Arrindell, de Vlaming, Eisenhardt, van Berkum, & Kwee, 2002). The main goal of this study was to provide the initial Spanish norms for the OCI-R and to examine its psychometric properties and factor structure in a sample

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of college students. We also wished to examine the possible sex differences in the OCI-R subscales, an issue that was not addressed in the previous reports (Foa et al., 2002; Hajcak et al., 2004). Although prevalence of OCD is similar in both genders, according to some clinical data the frequency of particular obsessive–compulsive symptoms may be different in men and women, with men showing more symmetry, order, and hoarding symptoms and women displaying more contamination and washing symptoms (e.g., Lensi, Cassano, Correddu, Ravagli, & Kunovac, 1996; Noshirvani, Kavsikis, Marks, Tsakiris, & Monteiro, 1991; Samuels et al., 2002). In non-clinical samples, gender differences have emerged in some studies of the Padua Inventory (Sternberger & Burns, 1990), although others (Kyrios, Bahr, & Wade, 1996) found no such differences. Finally, we wished to examine convergent and divergent validity of the OCI-R, especially of its hoarding subscale, since the validity of this subscale has been questioned (Foa et al., 2002). For this purpose, we included an additional measure of hoarding, the Saving Inventory—Revised (SI-R; Frost, Steketee, & Grisham, 2004).

2. Method 2.1. Participants The sample consisted of 381 undergraduate students (291 female, 85 male, 5 unspecified) from two different Spanish universities (University of Balearic Islands and Autonomous University of Barcelona). Ethical approval was obtained from the ethical committees of the two universities. Participation was voluntary and no payment or course credits were offered to the participants. The mean age was 21.09 years (S.D. = 2.65). 2.2. Measures 2.2.1. Obsessive–Compulsive Inventory—Revised (OCI-R) The OCI-R (Foa et al., 2002) is a 18-item self-administered questionnaire designed to assess distress associated with obsessive–compulsive symptoms. It requests a response on a 0–4 scale. The total OCI-R score is the sum of all items and it ranges from 0 to 72. The original version of the OCI-R was translated to Spanish by two of us (D.M.C. and M.A.F.) and back-translated by a professional bilingual translator. The translated version was then reviewed by the authors in order to verify the accuracy of the translation. The Spanish OCI-R is available from the first author upon request. 2.2.2. Padua Inventory (PI) The Spanish version (Mataix-Cols, Sanchez-Turet, & Vallejo, 2002) of the PI (Sanavio, 1988) is a 60-item questionnaire that assesses the degree of disturbance

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caused by intrusive thoughts and rituals. Scores range from 0 to 240. Factor analyses have yielded a four-factor structure (two obsessive and two compulsive factors), replicated across different studies in non-clinical samples (Macdonald & de Silva, 1999; Mataix-Cols et al., 2002; Sanavio, 1988; Van Oppen, 1992). These factors are named: Mental Control, Checking, Impulses, and Washing. Its Spanish version has high internal consistency, good test-retest reliability, and acceptable discriminant and convergent validity (Mataix-Cols, Sanchez-Turet, et al., 2002). 2.2.3. Saving Inventory—Revised (SI-R) The SI-R (Frost et al., 2004) is a 23-item questionnaire designed to provide a comprehensive assessment of hoarding behaviors. It requests a response on a 0–4 scale about the extent to which the symptom described in each item is present. Factor analysis has identified three factors, named difficulty discarding, excessive clutter, and excessive acquisition. Scores range from 0 to 92. The Spanish version (Tortella-Feliu et al., submitted) also has a three-factor structure, good internal consistency and test-retest reliability, and moderate divergent validity. 2.2.4. Beck Depression Inventory (BDI) The Spanish version (Sanz & Va´zquez, 1998) of the BDI (Beck & Steer, 1987) is a 21-item self-report scale of depressive symptoms. Scores range from 0 to 64. The Spanish version has demonstrated good reliability and validity estimates in both non-clinical (Sanz & Va´zquez, 1998) and clinical (Vazquez & Sanz, 1999) samples. 2.2.5. State-Trait Anxiety Inventory, trait subscale (STAI-T) The Spanish version of the STAI-T (Spielberger, Gorsuch, & Luschene, 1982) was used to assess trait anxiety. The STAI-T is a 20-item questionnaire rated on a 0–3 scale. Total scores range from 0 to 60. It is one of the most used trait anxiety scales both in clinical practice and in experimental research. It has demonstrated sound psychometric properties. 2.3. Procedure All participants were administered the questionnaires in a group setting during a lecture period. A brief description of the purpose of the study was given and written consent was obtained. Since Hajcak et al. (2004) found significant order effects for the OCI-R and the MOCI, with lower means when each measure was presented second, a subset of participants (n = 284) completed the OCI-R first, followed by the PI and the other measures. The rest of participants (n = 97) completed the PI first, followed by the OCI-R and the other measures. Sixty-four individuals completed a second administration of the OCI-R one month later and constituted the sample for test-retest reliability.

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3. Results 3.1. Factor structure of the Spanish OCI-R We conducted a confirmatory factor analysis using AMOS 5.0 in SPSS version 11.5. We evaluated the fit of our data to the original six-factor structure by Foa et al. (2002), using the maximum likelihood estimation method. To facilitate comparability, we considered the same fit indices as Foa et al. (2002) and Hajcak et al. (2004). The model had a significant x2 [x2 (129) = 331.08, P < .0001], a Goodness-of-Fit Index (GFI) of .90, a Comparative Fit Index (CFI) of .90, a rootmean-square residual (RMR) of .05, and a root-mean-square error of approximation (RMSEA) of .06. Considering criteria by Hu and Bentler (1999) (adequate fit indices are GFI and CFI of .90 or greater and RMR and RMSEA values of .06 or lower) our results, except for the chi-square, indicate a good fit for the six-factor model, with similar values to those presented by Hajcak et al. (2004). We also tested a one-factor model, and as in Hajcak et al. (2004), most indices suggested a poor fit (x2 (135) = 952.41, P < .0001; GFI = .773; CFI = .62; RMR = .09; RMSEA = .12). Standardized parameter estimates are available from the first author on request. Based on the above results, we therefore used the original subscales developed by Foa et al. (2002) in all subsequent analyses. 3.2. Correlations among OCI-R scales Cohen’s, (1988) criteria were used to evaluate the size of the correlations. Correlations >.50 will be defined as ‘‘large’’, from .30 to .49 as ‘‘medium’’, and from .10 to .29 as ‘‘small’’. Correlations between each of the subscales and the total scale of the OCI-R were large but inter-correlations among the subscales were only moderate (ranging between .27 and .47), reflecting a relatively small overlap between them (see Table 1). 3.3. Normative data, internal consistency, and gender differences Table 2 shows the means, standard deviations and Cronbach’s a coefficients for the total OCI-R and each of its subscales. For the whole sample, the mean score for the OCI-R was 15.59 (S.D. = 9.34; range = 1–55), which was slightly lower than previous studies with similar samples: 18.82 in Foa et al. (2002) study and 18.91 in Hajcak et al. (2004) study. Men tended to score higher than women but this difference did not reach statistical significance [t (367) = 1.95, P = .051]. Internal consistency for the full scale of the OCI-R was good (a = .86). Regarding the subscales, internal consistency was good for the obsessing subscale, acceptable for the checking subscale and moderate for the rest of subscales. As in previous studies of both the OCI-R (Foa et al., 2002; Hajcak et al., 2004) and the OCI (Wu & Watson, 2003), the neutralizing subscale had the lowest

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Table 1 Correlations among OCI-R subscales* Subscale

Obsessing

Hoarding

Ordering

Checking

Neutralizing

Total

Washing Obsessing Hoarding Ordering Checking Neutralizing

.34

.34 .38

.35 .27 .42

.41 .35 .40 .30

.45 .44 .43 .27 .47

.65 .71 .73 .65 .70 .69

*

All P-values <.001.

alpha. Men scored significantly higher than women on the hoarding (M = 4.34, S.D. = 2.60 vs. M = 3.71, S.D. = 2.39; t (373) = 2.08, P = .038) and checking (M = 2.74, S.D. = 2.53 vs. M = 2.19, S.D. = 2.17; t (372) = 1.97, P = .049) subscales. 3.4. Test-retest reliability (one month) Pearson’s r was calculated to assess the scale’s test-retest reliability. Our results for the OCI-R total score (.67) were similar to those of Hajcak et al. (2004), who obtained a test-retest reliability of .70 after the same interval. However, for the OCI-R subscales, the coefficients were somewhat smaller (washing: r = .45; obsessing: r = .57; hoarding: r = .56; ordering: r = .66; checking: r = .54; neutralizing: r = .50). 3.5. Convergent and divergent validity: OCI-R total and subscales To assess its convergent validity, the total and subscale scores of the OCI-R were correlated with scores on the PI and the SI-R (a measure of hoarding symptoms). Results are presented in Table 3. Table 2 Means, standard deviations and internal consistency (Cronbach’s a) for the OCI-R total scale and subscales, for the whole sample and by gender Males

OCI-R Washing Obsessing Hoarding Ordering Checking Neutralizing

Females

Total

a

M

S.D.

M

S.D.

M

S.D.

17.30 1.37 3.42 4.34 4.16 2.74 1.20

10.85 2.04 3.32 2.60 2.38 2.53 1.79

15.04 1.17 3.24 3.71 4.01 2.19 0.82

8.75 1.58 2.84 2.39 2.57 2.17 1.39

15.59 1.24 3.28 3.85 4.06 2.31 0.91

9.34 1.77 2.95 2.44 2.53 2.27 1.50

.86 .63 .82 .69 .67 .77 .61

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Table 3 Convergent validity of the OCI-R* OCI-R scale

Padua Inventory

Total Washing Obsessing Hoarding Ordering Checking Neutralizing

.52 .60 .27 .37 .37 .31 .35

*

Saving Washing Checking Impaired mental control Impulses Total Inventory—Revised .55 .42 .32 .34 .32 .49 .37

.54 .36 .51 .39 .23 .33 .28

.37 .30 .30 .23 .18 .26 .23

.62 .49 .46 .44 .34 .44 .36

.49 .30 .39 .47 .23 .29 .32

All P-values <.001.

The OCI-R total score showed a large correlation with the PI total score (r = .62) indicating good convergent validity. The washing, checking, and obsessing subscales of the OCI-R correlated better with the corresponding washing, checking and impaired mental control scales of the PI, respectively, than with the other non-corresponding subscales, indicating adequate convergent validity. This was also true for the hoarding subscale of the OCI-R, which showed the strongest correlation with the SI-R total score. Not surprisingly, ordering and neutralizing subscales showed the smallest correlations since these symptoms are not adequately represented in the other scales. The correlations between the OCI-R, BDI and STAI-T scores were small to medium, suggesting adequate discriminant validity of the OCI-R (Table 4). As in the Hajcak et al. (2004) study, the obsessing subscale showed the highest correlations with the BDI. Controlling for the STAI-T and BDI, the partial correlation between the OCI-R and the PI was r = .58 (P < .001), further indicating its adequate convergent and divergent validity. 3.6. Order effects The total OCI-R score was not different when it was presented before (M = 15.45, S.D. = 9.36) of after (M = 16, S.D. = 9.33) the PI [t(372) = 0.50, Table 4 Divergent validity for the OCI-R OCI-R scale

BDI

STAI-T

Total Washing Obsessing Hoarding Ordering Checking Neutralizing

.31 .28 .30 .16** .18 .17** .14*

.30 .20 .32 .18 .14* .19 .14*

All P-values <.001, except where indicated with *P < .05 or

**

P < .01.

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P = .61]. However, the total PI score was higher when presented before (M = 48.72, S.D. = 22.47) than after (M = 39.73, S.D. = 28.72) the OCI-R [t (216,270) = 3. 12, P = .002].

4. Discussion We examined the psychometric properties of a Spanish version of the OCI-R in a non-clinical sample. Overall, they were comparable to those of the original US version (Foa et al., 2002; Hajcak et al., 2004). For the total OCI-R scale, very similar estimates were obtained for internal consistency, test-retest reliability, and divergent validity. The slightly lower convergent validity in our study compared with the study by Hajcak et al. (2004) (.62 vs. .75) may be related to the fact that these authors used the PI-WSUR (Burns et al., 1996), a revised version of the PI which may overlap less with worry symptoms. Concerning the OCI-R subscales, we found similar internal consistency estimates to previous studies (Foa et al., 2002; Hajcak et al., 2004), except for the ordering and washing sub-scales, which had somewhat lower alphas. In agreement with these studies and with Wu and Watson (2003) study on the OCI, the neutralizing sub-scale had the lowest internal consistency. It seems important to further study the psychometric properties of this subscale, although it must be noted that low internal consistency values could be specific for non-clinical samples, since Foa et al. (2002) found good internal consistency estimates in several samples of patients with anxiety disorders. The convergent validity of the Spanish OCI-R subscales was moderate and their divergent validity was excellent. The washing, checking, and obsessing subscales had the highest correlations with the corresponding PI sub-scales and all subscales had small to medium correlations with measures of depression or trait anxiety. As in previous studies (Hajcak et al., 2004), the highest correlation with the BDI was obtained for the obsessing subscale, suggesting some overlap between these constructs. Importantly, dissipating concerns on the validity of the hoarding subscale (Foa et al., 2002), we found that this scale had the highest correlations with another measure of hoarding, the SI-R, thus supporting its convergent validity. Contrary to Hajcak et al. (2004), who reported order effects on repeated administrations of the OCI-R, we did not find such effects, which we did indeed find for the PI. Male students had marginally higher OCI-R total scores than females but this did not reach statistical significance. However, men did score higher than women on the hoarding and checking subscales. As noted, no data on potential sex differences were provided in the previous OCI-R studies. Sex differences have been previously reported in other self-report instruments, such as the Padua Inventory or the Maudsley Obsessional Compulsive Inventory both among patients (Richter, Cox, & Direnfeld, 1994) and normal subjects (Sternberger & Burns, 1990; Van Oppen, 1992) but no clear picture emerged

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from these studies. Checking symptoms may be more frequent among male OCD patients (Lensi et al., 1996; Noshirvani et al., 1991). At least in one study (Samuels et al., 2002) hoarding symptoms were twice as prevalent in male than in female OCD patients, although others (Mataix-Cols, Rauch, Manzo, Jenike, & Baer, 1999) found no such difference. It must be noted that some studies focused on the frequency of particular symptoms, while others focused on the severity of these symptoms. Future research should try to elucidate to what extent differences in the assessment procedure (symptom checklists versus severity scales) or in the populations under study (clinical vs. non-clinical) account for these previous inconsistencies. Finally, our confirmatory factor analysis suggested a good fit for a six-factor structure, thus replicating previous results on the OCI-R in both clinical (Foa et al., 2002) and non-clinical (Hajcak et al., 2004) samples. Overall, this factor structure is highly comparable to that obtained with other comprehensive inventories of OC symptoms, such as the Yale–Brown Obsessive Compulsive Symptom Checklist (Cavallini, Pasquale, Bellodi, & Smeraldi, 1999; Leckman et al., 1997; Mataix-Cols, Marks, Greist, Kobak, & Baer, 2002; Summerfeldt, Richter, Antony, & Swinson, 1999) and the recently developed Vancouver Obsessional Compulsive Inventory (Thordarson et al., 2004). Despite considerable differences between these instruments, at least four symptom dimensions have been consistently replicated in all studies, namely contamination/washing, checking, symmetry/ordering and hoarding. These converging results strongly suggest that OCD may be best conceptualized as a spectrum of potentially overlapping syndromes rather than a unitary nosological entity (see Mataix-Cols, Rosario-Campos & Leckman, in press, for a review). The psychometric properties of the Spanish OCI-R need to be further examined in clinical samples. It will be important to ascertain its ability to discriminate OCD from other types of anxiety and from depression. Another thus far unexplored question is whether the OCI-R is sensitive to treatment effects. In sum, the Spanish version of the OCI-R seems to retain the sound psychometric properties of its original version. Although further research is needed, it seems to be an excellent instrument for the assessment of obsessive– compulsive phenomena and can be used in other cultural contexts.

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