Contrary to most previous studies of the PID-5-BF in other countries, in this study, we found that a six-factor model was more suitable than the theoretical five-factor model for the PID-5-BF in our Chinese sample. Following modifications, our six-factor PID-5-BF model achieved configural MI, weak MI, strong MI, and partial strict MI across our normal and clinical samples. In agreement with prior studies [14, 20], we found that the PID-5-BF was highly correlated with the original 220-item PID-5 and the domains generally correlated with the six PDs retained in Section III of the DSM-5. We obtained acceptable Cronbach’s α and MIC values for the PID-5-BF [46], revealing a good internal consistency of PID-5-BF, similar to prior studies [16, 17, 20]. Furthermore, our finding of good test-retest reliability over a 4-week interval is in agreement with prior work showing similarly good test-retest reliability of the PID-5-BF over a 2-week interval in a sample of high school students [16].
Factor structure
Although a number of prior studies conducted in Western-culture populations have supported a five-factor model for the PID-5-BF [14, 15, 16, 19, 20], our results supported a six-factor model better than the theoretical five-factor model derived from the literature. Interestingly, a prior study conducted with Filipino college students also showed a relatively poor fit of the theoretical five-factor model for the PID-5-BF [22]. Thus, we speculate that the discrepancy may reflect differences in the way people from Western versus Eastern cultures understand personality constructs and thus interpret items of the PID-5-BF.
Four of the factors in our exploratory six-factor model were consistent with the theoretical five-factor structure. Only the Negative Affect domain failed to align, and items 10 (fear being alone) and 19 (I crave attention) were placed in the newly added factor called Interpersonal Relationships. According to traditional personality theories in Western cultures, which focus on internal characteristics of the individual [48], loneliness is regarded as a source of distress related to experiencing a lack of empathy. On the contrary, in Eastern cultures, which are generally more collectivist, individuals are often considered to be inherently closely connected with others [49]. Accordingly, loneliness may be viewed as an isolated state due to poor interpersonal skills. Item 19, which is associated with the Antagonism domain of the original PID-5-BF, refers to behaviors that put the individual at odds with others, including an exaggerated sense of self-importance and an expectation of special treatment [10]. However, in a collectivist society, one’s sense of belonging is an important aspect of his or her personality constitution [49]. Consequently, item 19 is likely to be understood as one’s desire to fit into a certain group and to communicate with others. Prior studies have explored the influences of collectivist versus individualist cultures on personality [50–52]. In summary, cultural differences in how one understands and interprets Items 10 and 19 may affect the factor loading of these two items.
The unique structure of the DSM-5 personality trait model in Chinese respondents, compared to respondents from most other examined countries, may be related to cultural differences in general personality models [35, 53]. Although the five-factor model has been widely used globally, it may not be fully applicable in a variety of cultural contexts due to its Western-centric derivation. Consistent with this supposition, the five-factor model was not well-fitted when the NEO Personality Inventory was examined in the Philippines [54], Korea [55], and Japan [56]. Hence, it appears that the Big-Five Model does not fully explain personality traits in collectivist society contexts [23]. Prior studies have proposed a six-factor hypothesis of Chinese personality traits, with the addition of Interpersonal Relationships [25]. The importance of this sixth dimension for Chinese personality analysis has been affirmed in Chinese Personality Assessment Inventory standardization studies [24]. Therefore, although many western personality tests are reasonably reliable and valid when applied to Chinese samples, there are some cultural deviations to be considered [25].
To the best of our knowledge, this study is the first to explore MI of the PID-5-BF. Establishment of MI provides evidence of a consistent underlying structure across groups and thus enables group means to be compared [30]. When performing nested MI modeling, as was done here with configural, weak, strong, and strict MI, MI must be established sequentially from lower- to higher-level MI analyses [57]. We were able to achieve MI fully with respect to factor structure (configural MI), metric (weak MI), and intercept (strong MI) equivalences for the PID-5-BF in both samples. Strict invariance was partially satisfied.
Because our modification index analyses led us to release constraints on Items 14, 4, 12, 20, 7, 15, 5, and 17 to better achieve strict invariance, it can be deduced that the residual variances of these items were not equivalent across our two sample groups. Notwithstanding, upon achieving strong MI, we were able to conclude that our finding of higher PID-5-BF scores in our clinical sample, compared to our normal sample, could be considered a reliable finding. Moreover, these data affirm a satisfactory discriminant validity of the PID-5-BF for differentiating between nonclinical and clinical individuals.
External validity and clinical value
Although the 220-item PID-5 has many merits for personality diagnosis—such as close relations with clinical symptoms, the ability to be combined with various psychotherapy methods, and good stability over time [12]—its length hinders its clinical utility. Pires et al. (2018) examined the psychometric properties of the 220-item (original), 100-item (short form), and 25-item (brief form) PID-5 versions in a sample of Portuguese university students and concluded that any of the three could be used to assess maladaptive personality traits reliably and validly [18]. Bach et al. (2016) compared the three forms in a Danish population and showed that the three scales were highly similar with respect to internal consistency, factor structure, discriminant validity, and correlation with DSM-4 PD dimensions [14]. The present findings of very strong correlation coefficients between the PID-5-BF and the 220-item PID-5 in both of our samples indicate that in addition to saving time, reducing the burden upon participants, and being generally more clinic friendly, the PID-5-BF maintains the validity of the original instrument to a remarkable degree.
Moreover, the six factors of the PID-5-BF in our six-factor model showed good alignment with the six PDs in Section III of the DSM-5. Each PD correlated directly and specifically with its expected domain, with the exception of obsessive-compulsive personality disorder, which demonstrated good continuity from the DSM-4 to the DSM-5. Our unexpected finding of the Psychoticism domain showing strong correlations with most of the PDs in our normal sample may due to college students being sensitive to abnormal behaviors, thereby limiting the specificity of Psychoticism. In summary, the PID-5-BF retained satisfactory psychometric properties, despite its extensive omission of items relative to the 220-item PID-5, affirming its suitability as a preliminary clinical PD screening tool.
The PID-5-BF can be used to differentiate between psychologically healthy and troubled respondents, at least preliminarily. Bach et al. (2016) reported that the PID-5-BF has very good discriminant validity between psychiatric outpatients and community-dwelling individuals [14], consistent with our findings of significantly higher PID-5-BF scores in our clinical patients than in our normal sample of undergraduate students. Clinicians can administer the PID-5-BF to acquire a rough estimation of one’s personality functioning, laying the foundation of further treatment planning, and then judge the need for additional assessments. Although the PID-5-BF may not provide unique clinical information regarding specific symptoms, it can describe personality traits through the assessment of dimensions, embodying differences in degree rather than in category, contributing to individualized therapy development.
Limitations and future directions
The present study had three noteworthy limitations. First, the retested sample and clinical population were relatively small due to practical limitations. Second, the clinical sample was heterogenous, including patients diagnosed with various psychological disorders. Third, the current study was cross-sectional, and cross-sectional studies cannot demonstrate predictive validity with the robustness of longitudinal studies. Hence, there is a need for larger longitudinal and clinical-sample studies of the PID-5-BF, particularly with samples constituted by patients with PDs.
Regarding future directions of research, because dimensions represent continua from normal to abnormal, actionable score ranges need to be established based on ample empirical data collected in clinical practice rather than developed from theoretical hypotheses. Further correlational analyses between the PID-5-BF and other psychological scales are also needed to clarify dimensional distinctions among different psychiatric diagnoses. MI should also be further examined across genders, age bands, and cultures, particularly in Asia and the Pacific Islands.