To enable easy assessment of pain catastrophizing and designed appropriate interventions targeting this psychological construct in Hausa LBP population, this study described the development of the Hausa-PCS through translation and cross-cultural adaptation of the original PCS into Hausa, and finally validation of the translated version in mixed urban and rural individuals with chronic LBP. The results of the study suggested that the Hausa-PCS was comprehensible, valid, and reliable when evaluating catastrophic thinking related to pain in Hausa-speaking individuals with chronic LBP.
The PCS was fairly simple to translate as there were no serious translation issues encountered. The items of the questionnaire were comprehensible during the field verbal pretesting with urban and rural participants. The translators ensured that standard Hausa wordings and phrases were used for easy understanding in both urban and rural contexts with the goal of achieving conceptual equivalence rather than literal translation. Although no ceiling or floor effects were observed in the total score or the subscales similar to reports of previous studies [39,69], however, ceiling effects were seen in 8 out of the 13 items whereas floor effects were seen in only 3 items. In line with our findings, ceiling effects in more than half of the PCS items were also reported in the Norwegian validation . In contrast, respondents exhibiting floor and ceiling effects were removed in the validation of the Simplified Chinese PCS among chronic pain patients .
The mean total score of the Hausa-PCS was 30.0 comparable to both the urban (30.2) and rural (29.9) respondents, indicating that the studied population experienced a high level of pain catastrophizing considering the report that pretreatment score of greater than 24 was associated with high follow-up pain outcomes . Thus, it can be inferred that individuals with pain catastrophizing scores greater than 24 as in the case of our sample may warrant interventions targeting to reduce pain catastrophizing. Similar to the Simplified Chinese version of the PCS , the content validity of the Hausa-PCS in terms of skewness was acceptable as all the items were less than 1.96, suggesting a response trend for normally distributed scores.
The PCS has been widely reported as three-factor structure consisting of the rumination, magnification and helplessness subscales following exploratory factor analysis [20,33,35-38,40,41,43,59,67] even though minor differences exist regarding how the PCS items loaded onto factors. A two-factor structure has been also reported in the literature [20,44,68,71-73]. In the present study, the CFA suggests that the three-factor structure proposed by Sullivan et al.  had the best fit for our sample compared to the one-factor or two-factor structure proposed by Chibnall and Tait  as indicated by the low SRMR and RMSEA and high CFI and TLI values. This finding is similar to the reports of many validations conducted in different samples of individuals with chronic pain [35,71-73]. On the contrary, other validations found the two-factor structure of the PCS to exhibit adequate model fit [44,68]. In another vein, Huijer et al.  found the one-factor, two-factor (based on the authors’ exploratory factor analysis) and Sullivan’s original three-factor structures to exhibit adequate fit to Arabic population. However, it is important to note that the differences in the factor structure of the PCS across studies may be attributed to cultural differences in different countries.
According to the recommendations of the quality criteria for measurement properties of health status questionnaires , construct validity of a measurement is supported when at least 75% of the predefined hypotheses are verified. Based on our a priori hypotheses that the Hausa-PCS total scores would correlate moderately to strongly with the criterion variables, the construct validity was supported as 83% (5 out of 6) of the hypotheses were confirmed. The questionnaire demonstrated strong positive correlation with NPRS (rho = 0.74) comparable to that obtained for the Hindi version (rho = 0.65)  and higher than that (rho range = 0.19–0.52) reported by many other adapted versions [29,32,35-37,39,40,73]. The moderate correlation obtained with the FABQ-physical activity (rho = 0.32) and FABQ-work (rho = 0.36) subscales were smaller compared to that obtained for the German (FABQ-physical activity; rho = 0.51 and FABQ-work; rho = 0.61) and Turkish (FABQ-physical activity; rho = 0.49 and FABQ-work; rho = 0.47)  versions but comparable to the Norwegian version  (FABQ-physical activity; rho = 0.34 and FABQ-work; rho = 0.25) except for the FABQ-work subscale which was found to be very low in the later version. Similarly, the moderate correlation obtained between our questionnaire and the ODI (rho = 0.35) coincides with the 0.35 obtained in the Hindi version  but slightly lower than the range of 0.40–0.57 obtained by other versions using the Roland-Morris Disability Questionnaire [35,36,69]. This variation in correlations values across studies could be explained for the different questionnaires used in the assessment of functional disability. In another vein, the Hausa-PCS correlated weakly with the MCS-12 scores (rho = –0.20) contrary to the Malay version which demonstrated moderate significant correlation with the MCS-12 (rho = –0.38).
The result of the known-groups validity of the Hausa-PCS revealed that the questionnaire and its subscales are not influenced by socio-demographic variables in terms of gender and habitation. Although this aspect of validity may require further investigation, it can be deducted based on the sample studied that male and female as well as urban and rural patients are likely to experiences the same level of pain catastrophizing as a result of chronic LBP. In contrast, the Persian version demonstrates its ability to differentiate male and female patients with non-malignant musculoskeletal pain .
Regarding internal consistency, the Hausa-PCS total score exhibited adequate internal consistency (α = 0.84) consistent with the original English version (α = 0.87)  and the range of 0.84–0.93 reported by many validation studies [32-34,36-39,41]. However, we obtained lower alpha coefficients for the rumination (α = 0.69) and magnification (α = 0.41) subscales but sufficient for the helplessness subscale (α = 0.78). Consistent with our findings, most previous studies [33,36,39,67,73] found lower alpha coefficients for the magnification subscales, which could be attributed to the small number of items peculiar with the three-factor structure. It is important to note that increasing the number of scale items typically increases the Cronbach's alpha . Thus, caution should be exercised when considering the magnification as independent subscale in computing pain catastrophizing. Consequently, the two-factor structure of the PCS may be considered but warrants further investigation.
The test-retest reliability of the Hausa-PCS total score was highly adequate (ICC = 0.90), suggesting excellent reproducibility. Our value is higher than the original English version (ICC = 0.73)  and the range of 0.76–0.85 obtained by several language versions [29,33,35-39,41,43], consistent with the 0.90 obtained for the Afrikaans , Nepali , and Xhosa  versions but slightly lower than the range of 0.92–0.97 obtained by other language versions [32,34,40,67]. However, for the Hausa-PCS subscales, the ICC was only adequate for the helplessness subscale (ICC = 0.89). The magnification (ICC = 0.68) and rumination (ICC = 0.43) subscales had insufficient test-retest reliability which is consistent with the findings of previous validations demonstrating smaller ICC values for these subscales compared to the helplessness subscale [35-37]. These findings, thus, suggest that further investigation into the factorial structure of the Hausa-PCS may be useful.
The SEM and MDC at 95% CI were computed in this study to supplement the test-retest reliability since ICC does not account for the size of measurement error that is clinically meaningful . The smaller the SEM the better the reliability (precision) of the measure whereas the smaller the MDC the more sensitive is the measure . In the present study, the SEM (3.47) and MDC (9.62) values calculated for the Hausa-PCS total score were comparable to the values for the Afrikaans (SEM = 3.30; MDC = 9.00)  and Xhosa (SEM = 3.30; MDC = 9.30) ; lower than the values calculated for the Korean (SEM = 3.72; MDC = 10.3) , German (SEM = 4.6; MDC = 12.8)  or Norwegian (SEM = 4.60; MDC = 12.8)  versions; but higher than the values for the Hindi (SEM = 1.90; MDC = 5.26)  and Nepali (SEM = 2.52; MDC = 6.98)  versions. Compared to the SEM and MDC values of the Hausa-PCS total score, the three subscales of the questionnaire demonstrated lower values consistent with the reports of prior studies [31,39,67]. Regarding our SEM for the Hausa-PCS total score (3.47), it can be interpreted that if an individual has a baseline total score of 29, we can be 95% confident that the true score lies between 25.5 and 32.5. As for the MDC (9.62), a change of 9.7 can be considered as a true change in the total score above measurement error. Additionally, the result of the Bland-Altman plot for the Hausa-PCS total score showed minimal bias as the mean difference (0.87) calculated was close to zero, with LOA95% of –8.10 to 9.75 which lies within the range of –15.1 to 16.0 reported in the literature [39,40,67,68]
One strength of this study is that the translation and cross-cultural adaptation was conducted as per the recommendation of guidelines outlined by Beaton et al. . Additionally, the psychometric evaluation was conducted and reported in line with the COSMIN guidelines  even though we did not use the global rating of change scale to confirm the respondents’ stability for reliability assessments. However, one potential limitation of this study is that the correlations of Hausa-PCS with the criterion variables used were based on cross-sectional data. Thus, any causal conclusion concerning the influence of pain catastrophizing on pain intensity, functional disability, fear-avoidance beliefs and mental health could not be drawn. Another potential limitation is that we were unable to evaluate responsiveness. Furthermore, divergent validity, which is another essential measure of construct validity, was not evaluated in the present study. Studies are needed to examine the causal relationships between Hausa-PCS and the aforementioned criterion measures in this population. Moreover, future researches evaluating responsiveness and divergent validity of the Hausa-PCS would be useful