1. Background
Depression is enshrined and viewed in two official classifications: The International Classification of Diseases 10th edition (ICD-10) (1) and Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5) (2). These official classifications address depression as a severe and widespread (2-4) clinical syndrome defined by the presence of specific clinical features not requiring a specific etiology but considers the possibility of both psychological and biological causative factors.
Depressive symptoms affecting thoughts, feelings, and activities of daily living, must be present for at least two weeks before a patient can be diagnosed as having depression (2, 4). Some symptoms of depression include persistent sadness, anxiety, hopelessness, worthlessness, loss of interest in previously pleasurable activities, pessimism, sleep disturbances, changes in appetite and weight, difficulty concentrating, as well as suicidal thoughts, plans, or attempts (1-4).
There is a high prevalence of depression in Nigeria (5-7). The World Health Organization (WHO) reported that seven million Nigerians and more than 322 million people globally suffer from depression (6). However, independent Nigerian studies reported higher prevalence rates of 26.2%, 17.5%, and 49.8% among the Nigerian elderly, internally displaced people (IDP) camp dwellers in Northern Nigeria, and university undergraduates in southwestern Nigeria, respectively (8-10).
Also, World Bank study reported that one in five Nigerians has depressive symptoms, and about 22% of Nigerians suffer chronic depression (11).
A growing concern is that depression among Nigerians is more common than is known, resulting from widespread ignorance and limited knowledge of depression and available mental health services (12). For instance, a study among Nigerian health practitioners reported that about 78% had limited knowledge of depression and difficulties working with depressed patients (13).
1.1. Justification for the Study
Judging from the growing rate of depression due to challenges ranging from insecurity, insurgencies, poverty, and unemployment (6, 11), there is a need for a standardized scale to diagnose depression among the Nigerians. This will provide more accurate statistics and proffer workable policy statements to address it. This argument thus underscores the need for an indigenous scale to measure depression because the most available standardized depression scales used in Nigeria are imported and, at best, validated by Nigerian authors before use. Often, these imported scales fail to consider peculiar socio-cultural factors germane to Nigerians.
2. Objectives
We aimed to develop and validate an indigenous scale to measure depression.
3. Methods
3.1. Item Generation for Redeemer’s University Depression Scale (RUDS)
Based on the clinical features of depression in both the DSM and ICD, the initial 32 items for Redeemer’s University Depression Scale (RUDS) were generated (2, 14-17). Items were then subjected to 12 expert opinions, eight clinical psychologists, two developmental psychologists, and two industrial psychologists with a minimum of ten years of work experience. The justification was that the expert technique is an acceptable method for content validity (18). As summarized in Table 1, 21 items were generally agreed upon by the experts to meet face value at 75%. The concordance inter-rater reliability was 0.97, which was above the stated level of acceptance for face values. Acceptable interrater reliability (r = 0.097, P = 0.000) was observed in the scores of the 12 experts for the items of RUDS. Finally, the instrument included 21 items used for Item Refinement.
Table 1.Interclass Correlation Showing the Interrater Reliability Index for Redeemer’s University Depression Scale
| Intraclass Correlation | 95% CI | ||||
|---|---|---|---|---|---|
| Lower Bound | Upper Bound | Value | Sig | ||
| Single Measures | 0.496 | 0.318 | 0.745 | 29.487 | 0.000 |
| Average Measures | 0.966 | 0.931 | 0.988 | 29.487 | 0.000 |
Abbreviation: CI, Confidence Interval
3.2. Exploratory Factor Analysis
The 21 items of the RUDS were subjected to an exploratory factor analysis (EFA). Principal components analysis (PCA) was used as the factor analysis technique. To confirm the adequacy of items for PCA, Bartlett’s test (19) was used. In addition, to assess factorability, the KMO measure of sampling adequacy (20) was used.
3.3. Item Refinement
The 21 items of RUDS were subjected to EFA. Factors with eigenvalues > 1 were extracted at the first stage of EFA. Next, the statistics for factors with eigenvalues > 1 were scrutinized. Stevens (21) recommended 0.40 as the least factor loading. However, only items loading < 0.45 on the items of RUDS were removed to improve its interpretability. The different plausible factor solutions were evaluated considering the items’ content and the proportional construct of interest.
3.4. Participants
In this study, 86 university undergraduates (male: 36 vs. female: 50) were drawn using the online survey method (google form) for the EFA of RUDS. The age range was between 15 and 34 years (mean = 19.72; SD = 3.61), 85 participants were single, and one was married. Twenty-eight participants were in 100 level of study, while 26, 20, and 12 participants were in 200, 300, and 400 levels of study, respectively.
A fresh sample of 456 undergraduates of a private university and a Federal Polytechnic, Osun State, Nigeria, was used to determine the psychometric properties of RUDS. A Google form was employed, generating responses from 300 university undergraduates, while questionnaires were administered to 156 polytechnic undergraduates.
Studies at both international (22) and Nigerian levels (5, 7, 23) showed that the age group of 18 - 29 years reported the highest prevalence of depression; thus, we selected this population. Although previous studies have not identified the sample as the riskiest students in Nigeria, they were selected as representative of the student population. A total number of 542 undergraduates (86 in the EFA and 456 in the validations) participated in the study.
3.5. Study Instruments
The participants responded to RUDS, The Center for Epidemiology Studies Depression Scale (CES-D) by Radloff (24), and the General Health Questionnaire 12 (GHQ-12) by Goldberg and Williams (25).
The CES-D is a twenty-item instrument that measures levels of depression. The items of CES-D are measured on a 4-point Likert scale, and scores range from zero to 60. Higher scores on CES-D indicate more symptomatology. The author reported a high internal consistency of CES-D with a Cronbach’s α coefficient ranging from 0.85 to 0.90 (24).
4. Results
4.1. Exploratory Factor Analysis
According to Pallant (26), for factor analysis to be considered appropriate, Bartletts Test (BTS) should be significant (P < 0.05), KMO index should be in the 0 to 1 range, and the minimum value for suitable factor analysis should be set as 0.06 . The KMO and BTS were carried out to measure the factorability of the 21-item RUDS. The observed KMO measure of sampling adequacy was 0.89, which was within the recommended range of 0 to 1; the BTS was also significant (χ2 = 1133.647, df = 210, P = 0.000). This result supports the correlation matrix’s factorability. Hence, the authors conducted the PCA. The principal component extraction method’s test resulted in the extraction of four components (Table 2).
Table 2.Total Variance Explained
| Components | Eigenvalues | % of Variance | Cumulative % |
|---|---|---|---|
| 1 | 9.624 | 45.831 | 45.831 |
| 2 | 1.996 | 9.505 | 55.336 |
| 3 | 1.338 | 6.370 | 61.707 |
| 4 | 1.161 | 5.528 | 67.234 |
Table 2 shows the summary of PCA for the extracted four components for the 21-item measure for RUDS. The loading of the 21 items under the four components was presented in Table 3.
Table 3.Component Matrix of 21 Items of Redeemer’s University Depression Scale a
| Component Matrix b | ||||
|---|---|---|---|---|
| Component | ||||
| 1 | 2 | 3 | 4 | |
| 11. I felt empty | 0.833 | |||
| 8. I felt worthless | 0.831 | |||
| 10. I felt sad | 0.768 | |||
| 15. I was easily fatigued | 0.744 | |||
| 9. I felt hopeless about the future | 0.741 | |||
| 19. I felt unworthy and unlovable | 0.737 | |||
| 18. I felt unworthy of a nice relationship | 0.727 | |||
| 14. I felt I was not just as good as other people | 0.726 | |||
| 3. My mind dwelt more on negative events in my environment | 0.724 | |||
| 1. I felt that most events around me will turn out bad | 0.721 | |||
| 4. I thought my chances of failing far outweigh my chances of succeeding | 0.717 | 0.444 | ||
| 2. I had feeling that no matter what I did I would eventually lose everything | 0.692 | |||
| 5. I became worried about things that usually did not bother me | 0.690 | |||
| 13. I lost interest in things I used to find pleasurable | 0.660 | |||
| 12. I cried most of the time | 0.655 | |||
| 16. I had lost appetite and do not feel like eating | 0.629 | |||
| 7. I thought I was better off dead | 0.610 | |||
| 17. I had difficulty sleeping | 0.610 | |||
| 6. I found it difficult concentrating on what I was doing | 0.597 | 0.409 | ||
| 21. I had tried to kill myself | 0.848 | |||
| 20. I felt so guilty for my failures that I cannot forgive myself | 0.732 | |||
a Extraction method: PCA
b Four components extracted
The four components extracted are summarized in Table 3; the eigenvalues of the items loaded on these components exceed 1. The eigenvalues of the four components range between 9.624 to 1.161, with a percentage ranging from 45.831 to 5.528 (see Table 2).
Table 3 indicated that 19 of the 21 items loaded best in the first component, two items loaded best in the second component, and one item loaded in the third and fourth components.
Of the 19 items loaded in the first component, two items loaded in more than one component, rendering those items as complex structures. The identified complex structures and the two items loading on the second component were deleted from the scale.
According to Cattell’s scree test rule, the authors conducted the Cattell scree plot to ascertain and clarify the point to retain (27). The scree plot revealed a break after the first component with a cumulative percentage of 45.83 from the total variance. The first was retained for further investigation in the current research.
4.2. Measuring the of Reliability of Redeemer’s University Depression Scale
Values of the corrected item/total correlations (point-biserial) indicated discriminations in the items of RUDS. Values between 0 and 0.19 imply poor discrimination, 0.2 and 0.39 indicate good discrimination, while ≥ 0.4 imply very good discrimination. As observed in Table 4, the item with a value between 0 and 0.19 in the RUDS is item 21 (0.11). Item had a point-biserial value between 0.2 and 0.39 (0.28). The observed values of the point-biserial suggest that items with values below the very good discrimination should be deleted from the scale as this could indicate an ambiguous and confusing item to participants.
Table 4.Item-Total Statistics of Redeemer’s University Depression Scale
| Redeemer’s University Depression Scale | Scale Mean if Item Deleted | Scale Variance if Item Deleted | Corrected Item-Total Correlation | Cronbach’s Alpha if Item Deleted |
|---|---|---|---|---|
| 1. I felt that most events around me will turn out bad | 44.8333 | 271.707 | 0.680 | 0.928 |
| 2. I had feeling that no matter what I did I would eventually lose everything | 45.2619 | 272.268 | 0.643 | 0.929 |
| 3. My mind dwelt more on negative events in my environment | 44.8333 | 269.538 | 0.668 | 0.928 |
| 4. I think my chances of failing far outweigh my chances of succeeding | 45.0476 | 271.588 | 0.647 | 0.929 |
| 5. I became worried about things that usually did not bother me | 44.3929 | 269.567 | 0.625 | 0.929 |
| 6. I found it difficult concentrating on what I was doing | 44.1667 | 275.369 | 0.524 | 0.930 |
| 7. I thought I was better off dead | 45.3214 | 271.498 | 0.586 | 0.929 |
| 8. I felt worthless | 45.1071 | 262.772 | 0.818 | 0.925 |
| 9. I felt hopeless about the future | 45.1429 | 267.570 | 0.687 | 0.928 |
| 10. I felt sad | 44.4048 | 262.316 | 0.714 | 0.927 |
| 11. I felt empty | 44.6310 | 259.778 | 0.789 | 0.926 |
| 12. I cried most of the time | 44.9881 | 268.349 | 0.617 | 0.929 |
| 13. I lost interest in things I used to find pleasurable | 44.6310 | 269.947 | 0.612 | 0.929 |
| 14. I felt I was not just as good as other people | 44.4762 | 263.168 | 0.676 | 0.928 |
| 15. I was easily fatigued | 44.2976 | 266.187 | 0.692 | 0.928 |
| 16. I had lost appetite and do not feel like eating | 44.8571 | 270.365 | 0.596 | 0.929 |
| 17. I had difficulty sleeping | 44.7500 | 268.937 | 0.590 | 0.929 |
| 18. I felt unworthy of a nice relationship | 44.7857 | 262.941 | 0.674 | 0.928 |
| 19. I felt unworthy and unlovable | 44.8333 | 265.273 | 0.689 | 0.928 |
| 20. I felt so guilty for my failures that I cannot forgive myself | 44.5595 | 280.346 | 0.282 | 0.936 |
| 21. I had tried to kill myself | 45.3929 | 288.844 | 0.111 | 0.939 |
Reliability analysis was carried out to determine the internal consistency of the extracted 18 items of the RUDS. The internal consistency of RUDS among the Nigerian sample revealed a Cronbach’s coefficient (α) of 0.91, a Spearman-Brown coefficient of 0.90, and a Guttman Split-Half coefficient of 0.89.
The values of the corrected item/total correlations (point-biserial) of the refined items for RUDS showed a good discrimination value (≥ 0.02).
4.3. Measuring the Validity of the Redeemer’s University Depression Scale
Using the concurrent validity technique, RUDS was validated using two existing standardized scales of depression (CES-D) and psychological distress (GHQ-12). The correlation matrix of the three scales is summarized in Table 5.
Table 5.Correlation Matrixes of Redeemer’s University Depression Scale, Epidemiology Studies Depression Scale, and General Health Questionnaire 12
| RUDS | CES-D | GHQ-12 | Mean ± SD | |
|---|---|---|---|---|
| RUDS | 1 | 27.19 ± 17.87 | ||
| CES-D | 0.787** | 1 | 44.65 ± 10.74 | |
| GHQ-12 | 0.521** | 0.511** | 1 | 30.95 ± 7.79 |
Table 5 summarizes Pearson’s r of RUDS score, CES-D score, and GHQ-12 score. Significant positive validity coefficient exists between the RUDS score and the composite scores of CES-D and GHQ-12. The reported validity coefficient between RUDS and CES-D was r = 0.787, P = 0.000; while r = 0.521 and P = 0.000 was reported between RUDS and GHQ-12. This result proved that RUDS is valid among the Nigerian population in testing for depression.
4.4. Calculation of the Norms for the Redeemer’s University Depression Scale
The cutoff points for the RUDS were determined using the 95% confidence interval (CI) method. As summarized in Table 6, considering a 95% CI, the male population mean ranged between 34.4 and 40.6, based on 184 samples [37.5 (95% CI 34.4 to 40.6)]. The derived mean for the female population was between 40.3 and 46.8, based on 272 samples [43.5368 (95% CI 40.3 to 46.8)], while the group mean was between a range of 25.6 and 28.8, based on 456 samples [27.2 (95% CI 25.6 to 28.8)]. The lower limit of these intervals (i.e., mean score minus 2 standard deviation) of ≥ 34.4; ≥ 40.3, and ≥ 25.6 is considered the cutoff points for the male, female, and group samples, respectively.
Table 6.The 95% Confidence Interval of Cutoff Point Determination for RUDS by Sex
| Group Sample | Male | Female | |
|---|---|---|---|
| Margin of Error | 1.64 | 3.09 | 3.22 |
| Sample size | 456 | 184 | 272 |
| Sample mean | 27.193 | 37.5 | 43.5368 |
| Standard deviation | 17.87447 | 21.36925 | 27.13038 |
| 95% CI | 27.2 (95% CI 25.6 to 28.8) | 37.5 (95% CI 34.4 to 40.6) | 43.5368 (95% CI 40.3 to 46.8) |
| Cutoff point | ≥ 25.6 | ≥ 34.4 | ≥ 40.3 |
The final draft of the validated RUDS and the scores’ interpretations are itemized in Tables 7 and 8, respectively.
Table 7.The Final Draft of Redeemer’s University Depression Scale
| Items | Never | Hardly Ever (Less Than One Day) | A Little of the Time (1 - 2 Days in a Week) | Sometimes (3 - 4 Days a Week) | Most or All the Time (5 - 7 Days a Week) | Always (All Week Long) |
|---|---|---|---|---|---|---|
| Please indicate how often you have felt this way during the past weeks. | ||||||
| 1. I felt that most events around me would turn out bad | 0 | 1 | 2 | 3 | 4 | 5 |
| 2. I had the feeling that no matter what I did, I would eventually lose everything | 0 | 1 | 2 | 3 | 4 | 5 |
| 3. My mind dwelt more on negative events in my environment | 0 | 1 | 2 | 3 | 4 | 5 |
| 4. I think my chances of failing far outweigh my chances of succeeding | 0 | 1 | 2 | 3 | 4 | 5 |
| 5. I became worried about things that usually did not bother me | 0 | 1 | 2 | 3 | 4 | 5 |
| 6. I thought I was better off dead | 0 | 1 | 2 | 3 | 4 | 5 |
| 7. I felt worthless | 0 | 1 | 2 | 3 | 4 | 5 |
| 8. I felt hopeless about the future | 0 | 1 | 2 | 3 | 4 | 5 |
| 9. I felt sad | 0 | 1 | 2 | 3 | 4 | 5 |
| 10. I felt empty | 0 | 1 | 2 | 3 | 4 | 5 |
| 11. I cried most of the time | 0 | 1 | 2 | 3 | 4 | 5 |
| 12. I lost interest in things I used to find pleasurable | 0 | 1 | 2 | 3 | 4 | 5 |
| 13. I felt I was not just as good as other people | 0 | 1 | 2 | 3 | 4 | 5 |
| 14. I was easily fatigued | 0 | 1 | 2 | 3 | 4 | 5 |
| 15. I had lost appetite and did not feel like eating | 0 | 1 | 2 | 3 | 4 | 5 |
| 16. I had difficulty sleeping | 0 | 1 | 2 | 3 | 4 | 5 |
| 17. I felt unworthy of a nice relationship | 0 | 1 | 2 | 3 | 4 | 5 |
| 18. I felt unworthy and unlovable | 0 | 1 | 2 | 3 | 4 | 5 |
The RUDS is scored by adding up the items scores. Table 8 is a summary of the interpretation of the scores based on group and individual samples. The individual samples are categorized by gender.
Table 8.Interpretation of Redeemer’s University Depression Scale Scores
| Group sample | Male | Female | |
|---|---|---|---|
| Normal | 0 - 8 | 0 - 13 | 0 - 13 |
| Mild depression | 9 - 25 | 14 - 33 | 14 - 39 |
| Mild to moderate depression | 26 - 29 | 34 - 41 | 40 - 47 |
| Moderate to severe depression | 30 - 77 | 42 - 74 | 48 - 68 |
| Severe depression | 78 and above | 75 and above | 69 and above |
5. Discussion
To measure the depression among adolescents and adults, we developed and validated the RUDS through considering the Nigerian socio-cultural setting and using the approach described by Lynn (28). Lynn (28) recommended a two-staged approach: Development and generation of instrument items and evaluating the instrument’s item performance (validation). In generating the initial pool of items for the RUDS, the researchers reviewed clinical features of depression recorded in both the DSM-5 and ICD-10 (2, 14, 15, 16, 17).
The six main themes identified included ‘biased perception’ (selective attendance to adverse events and features in one’s environments), ‘cognitive distortions’ (a description of self, the future, and the world in negative terms), and ‘affective disturbances’ (manifestation of low mood, diurnal variation, and anhedonia). Other subthemes included ‘somatizations’ (characterized by changes in somatic state, including loss of energy, disturbance of sleep and appetite, pain symptoms, weight loss or gain, and other vegetative features), ‘relationship deterioration’ (characterized by poor interpersonal relationships, asociality, and perceiving the self as lonely and unworthy of love), and ‘suicidality’ (suicidal ideation, intention, and attempts) (2, 14-17). The generation of items relating to the agreed themes resulted in 32 items used for scale purification purposes. Also, a 6-point Likert scale was used to measure opinions, beliefs, and attitudes (29). Based on the decision to use a Likert response format, each item of the RUDS is a declarative statement (29).
As recommended by Flynn and Pearcy (30) and Derbaix and Pecheux (31), the combination of reliability analysis and EFA was used for the purification of RUDS.
The initial items generated by authors were subjected to content validity by a panel of experts. According to Streiner et al. (32), content validity presents currently available knowledge in the construct of interest. It is also the minimum quality requirement for an instrument (33, 34), an essential indicator of an instrument’s validity, and a display of how feasible and practicable an instrument is (33, 35). The development process of RUDS supported its validity and formed a basis for further examination of its validity and reliability.
The Cronbach’s α for RUDS was 0.91, and item-total correlation ranged from 0.52 to 0.81. The implication of this finding showed a good item inter-relatedness, unidimensionality, and homogeneity of the construct (36, 37) among the Nigerian population. In other words, the scores of Cronbach’s α, Spearman-Brown coefficient, and Guttman Split-Half coefficient were not too high to render some items as redundant (38, 39). In summary, the high alpha score showed that RUDS has a strong reliability.
As a new scale, the RUDS was validated using the concurrent validity method as recommended by Cronbach and Meehl (40). RUDS positively correlated with two standardized scales for measuring depression and psychological distress among the general population. Based on the EFA results and the acceptable psychometric properties. The RUDS is an adequate measure of depression for both adolescents and adults in Nigeria and other areas with similar socio-cultural settings.
5.1. Conclusions
In this study, through stages involving initial items generation, experts’ assessment (content validity) of the initial pool of items, and the use of EFA for items purification, a single factor scale with 18 items was extracted to make up the RUDS. The items of the RUDS showed an acceptable internal consistency (reliability coefficient). Also, RUDS had significant positive correlations with the CES-D and the GHQ-12, indicating an acceptable validity coefficient. Finally, the RUDS is gender-sensitive, as 95% CI revealed a lower cutoff point for male participants than females. We recommend the RUDS as a diagnostic tool for depression among adolescents and adults in Nigeria and other climes with similar socio-cultural settings.
5.2. Limitations of the Study
This research was carried out based on the unique psycho-sociocultural setting of the Nigerian population. The generalization of the findings and the use of this scale on other populations with different social-cultural characteristics without scale re-validation should be approached with caution.
