Shams, Kaviani, Esmaili, et al Original Article Psychometric Properties of the Persian Version of the Padua Inventory: Washington State University Revision (PI-WSUR) Giti Shams, PhD1 Objective: The psychometric properties and factor structure of the Hosein Kaviani, PhD 1 Persian Padua Inventory Washington State University Revision (PI- Yaghob Esmaili, MA2 WSUR), a measure of obsessive- compulsive phenomena, was Narges Ebrahimkhani, BA1 examined in a non-clinical sample of 348 Iranian university students. Alireza Amin Manesh, MD3 Method: The PI-WSUR was translated into Persian, and its back translation was controlled by the author inventory. A pilot study based on 1 Department of Psychiatry, cultural differences was carried out on twenty students. The study Tehran University of Medical subjects consisted of 348 university students, and they completed PPI, Sciences, Tehran, Iran OCI-R, MOCI, BAI, STAI, BDI-II and the demographic inventory. 2 Department of Psychology, Results: The factor analysis of the PI-WSUR, exhibited eight factors Rood-e-hen Azad University, similar but not identical with factor structure in previous studies. as the Tehran, Iran eight factors are as follows: contamination obsessions; washing 3 Treatment & Health Network of compulsions; ordering compulsions; checking compulsions; obsessional Rey State thoughts to harm self/others; obsessional thoughts about violence; obsessional impulses to harm self/others; and obsessional impulses to Corresponding author: steal. The result also indicated excellent internal consistency (Cronbach Giti Shams, PhD alpha= 0.92), Spearman split test (0.95) and test- retest (r= 0.77). We Assistant Professor of Clinical assessed the concurrent validity of the PPI in relation to the Obsessive Psychology, Department of Compulsive Inventory-Revised (OCI-R), and the Maudsley Obsessive- Psychiatry, Roozbeh Hospital, Compulsive Inventory (MOCI). South Kargar Ave., Tehran Conclusion: The Iranian version of the PI to some extend remains the 13337, Iran. sound psychometric properties of the original version.. Tel: +98-21-55419151 Fax: +98-21-55419113 Keywords: Iran, Obsessive compulsive disorder, Psychological tests, Email: [email protected] Psychometrics Iran J Psychiatry 2011; 6: 12-18 research settings (11, 12). Some researchers have S everal theoretical and psychometrically sound investigated sub-types of OCD symptoms (13-15); there is also an emerging consensus in the field that measures have been developed to assess the presence OCD is better conceptualized according to the and severity of OCD symptoms in community and dimensional model (16). Recently, Lee (17) proposed a clinical samples. Each type of instrument has unique model of obsessive thoughts that is pertinent to theories strengths and weaknesses. Multiple methods of of OCD as proposed by Rachman (18-20). They assessment are commonly used for OCD and spectrum suggested that obsessive thoughts can be classified into conditions, including formal diagnostic interviews, as two types of autogenous obsessions. well as interviews for gathering clinical information. Sanavio (3) developed the original Padua Inventory as At present, various self-report instruments are available the first major of self reported OCD symptoms. The to assist in the diagnosis and measurement of OCD. original Italian version of the PI added two obsessive The most widely accepted measures are: Leyton factors to the two traditional cleaning and checking Obsessional inventory short form (LOI) (1); The scales. The replication of the research across different Maudsley Obsessive-Compulsive Inventory (MOCI) cultures requires the use of a measure that has been (2); Padua Inventory-Washington State University standardized across those cultural contexts. It was a Revision (PI-WSUR) (3,4);Yale-Brown Obsessive- self report inventory that assessed the degree of Compulsive Scale-self-report (Y-BOCS-SR) (5); disturbance or difficulty of 60 different thoughts and Obsessive-Compulsive Inventory-Revised (OCI-R) (6); behaviors engendered for the individual with OCD. Vancouver Obsessional compulsive inventory (VOCI) The PI has been adopted in different countries. (7); Florida obsessive-compulsive inventory (FOCI) Some researches showed that original PI also measures (8); Schedule of compulsions, obsessions, and "worry" in addition to "obsessions" (30). The result pathological impulses (SCOPI,) (9); Clark-Beck from Kyrios, Bhar and Wade (21) study indicated that Obsessive Compulsive Inventory (CBOCI) (10). the PI exhibited a similar but not identical factor Nonetheless, those measures have several structure compared to previous studies. It was shortcomings, in terms of content or psychometric consisted of four factors which were termed as: (1) properties that limit their use in both clinical and 12 Iranian J Psychiatry 6:1, Winter 2011 Published by "Tehran University of Medical Sciences"(www.tums.ac.ir) Psychometric Properties of the Persian Version of the Padua Inventory (PI-WSUR) checking and repeating; (2) contamination fears, and subscales and α' of .92 for the total scale (4). Overall, orderliness; (3) impaired mental control; (4) urges and the PI-WSUR has demonstrated good psychometric worries. However, in Macdonald's study (22), four properties and reports showed an improvement of the factors emerged and were labeled as (1) impaired original PI. It has been demonstrated adequate 6 control over mental activities/ doubting; (2) months test-retest reliability (r= .76) in a styudy in contamination; (3) checking; (4) worries about losing Iceland (31). control over motor behavior. One of the best-supported Identification of stable, and homogeneous subgroups of factor solutions on PI was reported by Leckman (23), OCD patients may have important implications for who found four dimensions: (a) obsessions (aggressive, understanding variability in treatment response for sexual, religious, or somatic); (b) symmetry obsessions improving treatment effectiveness and may also and ordering, counting and repeating compulsion; (c) advance etiologic theory (26, 32). Cross-cultural contamination obsessions and cleaning compulsions; studies on the Padua Inventory indicate that PI-WSUR and (d) hoarding obsessions and collecting can define the similarities and differences of factors compulsions ;while Abramowitz (24) who clustered the involved in OCD concept across different cultures. broadest sampling of OC symptoms, obtained a five Hence, it was felt that a study of the PI-WSUR within cluster solution: harming; contamination; hoarding; the Iranian culture could be useful, and could provide unacceptable thoughts; and symmetry. Van Oppen (25) national measure for further study of obsessive- also evaluated the factor structure of the Padua compulsive phenomena within Iranian context. Thus, inventory (3), and identified the five following factors: our goal in this study was to make an assessment of a impulses; washing; checking; rumination; and Persian translation of PI-WSUR, to examine its precision. In Baer study (26), however, three factors psychometric properties and factor structure in an were found and labeled as symmetry and hoarding; Iranian sample of college students. contamination and cleaning; and pure obsessions. A factor analysis in Wakabayashi (27) study replicated a Materials and Method four-factor structure, consisting of three factors Participants corresponding to those found in previous studies The sample consisted of 348 (213 Male and 135 ('Impaired control of mental activity', 'Being female) volunteering students of Tehran University of contaminated' and 'checking behavior') and one factor Medical Sciences. The age range of the total sample ('Impulsive thought'), which partly differed from that was 18-44, having an average age of 21/85, with found previously. To examine psychometric properties standard deviation of 3/12. of PI, Goodarzi (28), collected data in the city of Shiraz ( Iran), and found good reliability for the PI and Measures confirmed its factorial structure reported by previous The Padua Inventory- Washington State University studies. Also, he was able to differentiate between Revision (PI-WSUR) (30): is a 39-item self-report OCD patients and normal individuals, but failed to measure of obsessions and compulsions (4). Each item differentiate between neurotic and OCD patients. Later is rated on a 5-point scale according to the degree of research demonstrated that obsessional subscales of PI disturbance caused by the thought or behavior (0= “not appeared to measure general "worry" (29). This at all” to 4= “very much”). The PI-WSUR items were problem has implication for the use of the PI, organized to measure 5 content areas relevant to OCD. particularly in studies that utilize the Padua to examine These 5 areas are obsessional thoughts to harm the relation between obsession and worry. Burns (30) self/others (OTAHSO); obsessional impulses to harm believed that if the Padua measures worry in addition self/others (OITHSO); contamination obsessions and to the obsessional aspect of OCD, then it becomes washing compulsions (COWC); checking compulsions difficult to differentiate between "obsession" and (CHKC); and dressing/grooming compulsions "worry". Thus, his aim was to determine the content- (DRGRC). The PI-WSUR demonstrated good internal based revision of the original PI and to provide a better consistency, with α's ranging from .77 to .88 on measure of obsessions and compulsions. Therefore, he subscales and α's of .92 for the total scale (4). (30) attempted to solve this measurement problem with Maudsley Obsessional-Compulsive Inventory (MOCI) initiation of Padua inventory-Washington State (33): MOCI is a 30-item true-false self-report University-Revised (PI-WSU-R) which contains 39- questionnaire that assesses overt rituals and their items each rated on a five point scale, indicating the related obsessions, providing four subscales and a total degree of disturbances caused by the symptoms. The score. The scale has been shown to have satisfactory revision was constructed to measure five content test-retest reliability (r= .80) and internal consistency dimensions relevant to OCD i.e., (1) obsessional (.70 to .80; (33). The MOCI's validity was found to be thoughts to harm oneself/ others; (2) satisfactory with the washing and checking subscales, obsessional/Impulses to harm oneself/others; (3) showing good discriminant and convergent validity contamination obsessions and washing compulsion; (4) (34). This inventory has been used with adequate checking compulsions; and (5) dressing/ grooming validity and reliability [13]. The Persian language compulsions. The PI-WSUR demonstrated good version of the test has been used in a number of studies internal consistency, with α' ranging from .77 to .88 on in Iran (35-37). Iranian J Psychiatry 6:1, Winter 2011 13 Published by "Tehran University of Medical Sciences"(www.tums.ac.ir) Shams, Kaviani, Esmaili, et al State-Trait Anxiety Inventory (STAI) (38): STAI is a Third, the Reliability of the PPI-WSUR was assessed 40-item self-report measure of general anxiety. The by two methods: test-retest and split-half. first 20 items assess state anxiety or how the participant feels "right now". The second 20 items Results assess trait anxiety, or how the participant feels "generally". The STAI has high reliability and validity Factor Structure of Persian Padua Inventory: (38). Only the state subscale (STAI-S) was used in the Washington State-University Revision (PPI-WSUR) present study. The STAI-Persian has excellent internal A confirmatory factor analytic model was used to consistency (Cronbach's a=.90) and test-retest examine the conceptual structure underlying the Padua reliability (r= .53) assessed in an Iranian student Inventory, the Persian version. These techniques sample (39). identify which items most strongly cluster together by Beck Depression Inventory (BDI-II) (40): BDI-II is the assessing the correlation between items within the second edition of the widely use Beck Depression instrument. Furthermore, the principal factor analysis Inventory. Originally introduced in 1960s (41). BDI-II (PCA) procedure was selected to identify the factor was revised to approximate the DSM-IV (42) criteria structure. This inventory has 39 items, therefore, factor for major depression. The reliability and validity of analysis was accomplished according to a matrix of various non-English versions of the BDI have been 39*39. The Olken-Meyer coefficient of sampling established in numerous previous studies. The BDI-II adequacy was 0.872 indicating that the sample is quite contains 21-item sets, each with a s eries of four representative ,and Bartlette test of sphericity was statements describing the severity of depressive highly significant (P<0.001) indicating that the symptoms along ordinal continuum from absent or correlation matrix does differ from an identity mild (scored 0) to severe (scored 3). Scores on this test correlation matrix. Extracted factors were rotated using can thus range from 0 to 63. The BDI-II-Persian has orthogonal factors method. We used Varimax rotation, excellent internal consistency (Cronbach's a=.87) and which minimizes the number of variables that have test-retest reliability (r= .73) assessed in Iranian student high loadings on each given factor. Rotation serves to sample (37). make the output more understandable and is usually Beck Anxiety Inventory (BAI) (43): BAI is a 21-item necessary to facilitate the interpretation of factors. anxiety symptom checklist that covers common anxiety After rotation, 8 factors explain 61.453% of the total symptoms commonly experienced by clinically variance observed. Initial Eigen values of 8 Factors anxious people. Scores on this test can thus range from were in order: 12.392%, 9.186%, 9.133%, 8.254%, 0 to 63. It has excellent psychometric properties. The 6.669%, 5.983%, 5.355%, and 4.480%. Factor loadings BAI-Persian has excellent internal consistency are the basis for imputing a l abel to the different (Cronbach's a=.92) and test-retest reliability (r=.87) factors. Observantly to nature of factors 1-8, we assessed in Iranian student sample (44). denominated them in order of (CONO), (WASC), The Obsessive-Compulsive Inventory-Revised (OCI-R) (ORDC), (CHKC), (OTAHSO), (OTAV), (OITHSO), (45) : The OCI-R is a new 18-item questionnaire based and (OITS). Table 1 shows that from the 39 items, 6 on the earlier 84-item OCI (6). The OCI-R assesses items(1,2,7,8,9,10) belong to factor one; Likewise, OCD symptoms across six factors: (1) washing; (2) factor two comprises 4 items(3,4,5,6);items of 11,12,13 checking/doubting; (3) obsessing; (4) mental belong to factor 3; factor 4 comprises 10 neutralizing; (5) ordering; and (6) hoarding. items(14,15,16,17,18,19,20,21,22,23); items of 24, Preliminary data suggest that the OCI-R possesses 25,26,27,30 belong to factor5; th sixth factor comprises good internal consistency (α's ranged from .81 to 93 of 2 i tems(28,29); factor 7 be long to items of across sample), and test-retest reliability (.57 to .91 31,32,33,34,35,36,39 and finally 2 i tems (37,38) across samples). A cutoff of 15 on the CI-R showed belong to factor 8. That is, the communality is the good sensitivity (84%) and specificity (78%) in its squared multiple correlation for the variable using the ability to distinguish individuals with OCD from non- factors as predictors (Table 1). clinical participants (45). The OCI-R-Persian has excellent internal consistency (Cronbach's a=.85) and Convergence validity of PPI-WSUR test-retest reliability (r=.75) assessed in Iranian student To calculate convergence, we assessed the correlation sample (46). of PPI-WSUR with OCI-R and MOCI. PPI-WSUR Statistical Analyses total was positively associated with OCI-R and MOCI The evaluations of the psychometric properties of the total (r= 0.699, r=0.587, p<0.01). PPI-WSUR was PPI-WSUR were as follows: First, using a associated with all OCI-R subscales (p<0.01) except confirmatory factor analytic model, the factor structure for PPI-WSUR-OITS with OCI-R-ordering. There was of the PPI-WSUR was assessed via Principal significant association between most of the PPI-WSUR Component Analysis (PA) with Varimax rotation. subscales and MOCI subscales (p<0.01) with two Second, the Convergence validity was computed by correlation of PPI-WSUR with OCI-R and MOCI. exceptions on PPI-WSUR-OITT with MOCI subscales, and PPI-WSUR subscales with MOCI-slow. 14 Iranian J Psychiatry 6:1, Winter 20 11 Published by "Tehran University of Medical Sciences"(www.tums.ac.ir) Psychometric Properties of the Persian Version of the Padua Inventory (PI-WSUR) Significant association was also observed between PPI- Cronbach’s Alpha coefficient were used. Scores on the WSUR and its subscales with BAI, STAI, BDI-II PPI-WSUR e were remarkably consistent in these two methods (Table3). (p<0.01) except for PPI-WSUR-OITS and STAI (Table 2). Discussion Reliability of PPI-WSUR A reliable test gives consistent results. Therefore, we The present study investigated the psychometric used two methods including time sampling and domain properties of the Iranian version of the PI-WSUR on a sampling. In the first method, test-retest reliability was large non clinical sample. assessed in two weeks (Inter-class). In the second method, split-half (spearman-Brown correlation) and Table1. PPI-WSUR -scale: Varimax-rotated Factor loadings for the 8-factor solution Factors Factor Loading Factor 1 Contamination obsessions (CONO) 1- I feel my hands are dirty when I touch money. .63 2- I think even slight contact with bodily secretions (perspiration, saliva urine, etc.) may contaminate my clothes or .75 somehow harm me. 7- I wash my hands more often and longer than necessary. .47 8- I sometimes have to wash or clean myself simply because I think I may be dirty or “contaminated”. .51 9- If I touch something I think is “contaminated”, I immediately have to wash or clean myself. .52 10- If an animal touches me, I feel dirty and immediately have to wash myself or change my clothing. .53 Factor 2 Washing compulsions (WASC) 3- I find it difficult to touch an object when I know it has been touched by strangers or by certain people. .59 4- I find it difficult to touch garbage or dirty things. .54 5- I avoid using public toilets because I am afraid of disease and contamination. .69 6- I avoid using public telephones because I am afraid of contagion and disease. .69 Factor 3 Ordering compulsions (ORDC) 11- I feel obliged to follow a particular order in dressing, undressing, and washing myself. .63 12- Before going to sleep, I have to do certain things in a certain order. .76 13- Before going to bed, I have to hang up or fold my clothes in a special way. .76 Factor 4 Checking compulsions (CHKC) 14- I have to do things several times before I think they are properly done. .54 15- I tend to keep on checking things more often than necessary. .50 16- I check and recheck gas and water taps and light switches after turning them off. .78 17- I return home to check doors, windows, drawers, etc., to make sure they are properly shut. .77 18- I keep on checking forms, documents, checks, etc., in detail to make sure I have filled them in correctly. .73 19- I keep on going back to see that matches, cigarettes, etc, are properly extinguished. .70 20- When I handle money, I count and recount it several times. .66 21- I check letters carefully many times before posting them. .69 22- Sometimes I am not sure I have done things which in fact I knew I have done. .59 23- When I read, I have the impression I have missed something important and must go back and reread the passage at .40 least two or three times. Factor 5 Obsessional thoughts about harm to self/others (OTAHSO) 24- I imagine catastrophic consequences as a result of absent-mindedness or minor errors which I make. .53 25- I think or worry at length about having hurt someone without knowing it. .74 26- When I hear about a disaster, I think it is somehow my fault. .73 27- I sometimes worry at length for no reason that I have hurt myself or have some disease. .67 30- I invent useless worries about germs and disease. .58 Factor 6 Obsessional thoughts about violence (OTAV) 28- I get upset and worried at the sight of knives, daggers, and other pointed objects. .69 29- When I hear about a suicide or a crime, I am upset for a long time and find it difficult to stop thinking about it. .63 Factor 7 Obsessional impulses to harm self/others (OITHSO) 31- When I look down from a bridge or a very high window, I feel an impulse to throw myself into space. .61 32- When I see a train approaching, I sometimes think I could throw myself under its wheels. .77 33- At certain moments, I am tempted to tear off my clothes in public. .51 34- While driving, I sometimes feel an impulse to drive the car into someone or something. .79 35- Seeing weapons excites me and makes me think violent thoughts. .70 36- I sometimes feel the need to break or damage things for no reason. .58 39- I sometimes have an impulse to hurt defenseless children or animals. .46 Factor 8 Obsessional impulses of Stealing (OITS) 37- I sometimes have an impulse to steal other people’s belongings, even if they are of no use to me. .82 38- I am sometimes almost irresistibly tempted to steal something from the supermarket. .84 Iranian J Psychiatry 6:1, Winter 2011 15 Published by "Tehran University of Medical Sciences"(www.tums.ac.ir) Shams, Kaviani, Esmaili, et al 1 6 S h Table 2. Correlation between PPI-WSUR (total and subscales) and OCI-R ،MOCI، BAI ،STAI ،BDI-II a m OCI-R MOCI BAI STAI BDI-II s Total Wash Chek Obssess Hoard Ord Neu Total Check Wash Slow Doubt , K Padua (PPI-WSUR -Total) .699** .672** .613** .570** .405** .435** .420** .587** .541** .429 .04 .462** .473** .402** .451** a v ia Padua (PPI-WSUR -CONO) .559** .689** .455** .400** .268** .368** .282** .481** .299** .437** .015 .357** .292** .225** .230** n i, E Padua (PPI-WSUR -WASC) .469** .553** .360** .343** .215** .335** .263** .385** .280** .429** .072 .292** .296** .228** .194** s m a P adua (PPI-WSUR -ORDC) .423** .437** .319** .333** .181** .359** .235** .381** .308** .282** .064 .336** .232** .183** .199** ili e Padua (PPI-WSUR -CHKC) .594** .509** .723** .485** .368** .301** .345** .541** .600** .319** .108 .404** .409** 322** .350** t a l Padua (PPI-WSUR -OTAHSO) .370** .491** .463** .561** .398** .354** .394** .462** .290** .245** -.030 .417** .458** .407** .462** Padua (PPI-WSUR -OTAV) .356** .290** .237** .388** .289** .171** .293** .261** .222** .168** -.006 .204** .302** .252** .246** Padua (PPI-WSUR -OITHSO) .356** .266** .242** .310** .276** .178** .346** .196** .197** .123** -.040 .171** .289** .236** .355** Padua (PPI-WSUR -OITS) .199** .157** .126** .152** .175** .064 .285** .01 .074 .104 .036 .033 .111** .079 .141** Contamination obsessions (CONO); Washing compulsions (WASC); Ordering compulsions (ORDC); Checking compulsions (CHKC); Obsessional thoughts about harm to self/others (OTAHSO); Obsessional thoughts about violence (OTAV); Obsessional impulses to harm self/others (OITHSO); Obsessional impulses to thieve (OITT) Table3.Reliability by Time sampling & domain sampling models Padua (PPI-WSUR) elements Cronbach’s Alpha split-half Test-retest Padua (PPI-WSUR -Total) .92 .95 .77 Padua (PPI-WSUR -CONO) .77 .82 .84 I r a n Padua (PPI-WSUR -WASC) .71 .77 .72 ia n J Padua (PPI-WSUR -ORDC) .74 .80 .75 P sy Padua (PPI-WSUR -CHKC) .87 .90 .83 c h ia Padua (PPI-WSUR -OTAHSO) .83 .89 .60 try 6 Padua (PPI-WSUR -OTAV) .56 .60 .40 : 1 , W Padua (PPI-WSUR -OITHSO) .86 .90 .62 in te Padua (PPI-WSUR -OITS) .80 .74 .78 r 2 Contamination obsessions (CONO); Washing compulsions (WASC); Ordering compulsions (ORDC); Checking compulsions (CHKC); Obsessional thoughts about harm to self/others (OTAHSO); Obsessional thoughts about 0 1 1 violence (OTAV); Obsessional impulses to harm self/others (OITHSO); Obsessional impulses of Stealing (OITS) 16 Iranian J Psychiatry 6:1, Winter 2011 Published by "Tehran University of Medical Sciences"(www.tums.ac.ir) Psychometric Properties of the Persian Version of the Padua Inventory (PI-WSUR) The eight content categories are as follows: References contamination obsessions (CONO); washing compulsions (WASC); 1. 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