Psychometric properties the of Brazilian Portuguese version of Snaith-Hamilton Pleasure Scale (SHAPS)

Abstract Introduction Anhedonia is defined as the reduced ability to feel pleasure and is a core symptom of various psychiatric disorders such as depression and schizophrenia. The Snaith-Hamilton Pleasure Scale (SHAPS) was developed to assess the presence of anhedonia. The objective of this study was to assess the psychometric properties of the Brazilian Portuguese version of the SHAPS. Methods In this study, the SHAPS (14 items) was translated into Brazilian Portuguese and validated using data obtained from 228 subjects within a clinical sample. Psychometric properties were assessed using item response theory (logistic models) and classical test theory (Cronbach’s alpha). We checked for external validity using a non-parametric correlation with an independent scale: Hospital Anxiety and Depression Scale – Depression subscale (HAD-D). Results The SHAPS presented good internal consistency, with a Cronbach’s α coefficient of 0.759 and adequacy to an IRT 1 parameter logistic (Rasch) model. The SHAPS presented significant correlation with the external measure HAD-D, with Spearman’s ρ = 0.249 (S = 1368914; p < 0.001). Conclusion These results suggest that the Brazilian Portuguese version of the SHAPS is a reliable and valid instrument to assess hedonic tone.


Introduction
Hedonic tone has been a subject of notable interest in the area of mental health. Anhedonia is defined as the loss or reduction of the ability to feel pleasure; it is a central feature of major depression and is present in schizophrenia. 1 The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) includes symptoms of interest or pleasure in the diagnostic criteria of major depression. 2 Anhedonia is also a symptom of dementia and one of the non-motor symptoms of Parkinson's disease. 3 Research on anhedonia has contributed to the investigation of psychiatric biomarkers, mainly in depression, schizophrenia, Parkinson's, and Alzheimer's diseases. 4 According to published data, it is still unclear whether anhedonia is a stable behavioral trait or a fluctuating state dependent on the severity of the disease, even after remission of the symptoms of a depressive episode. 5,6 Different scales have been proposed to measure anhedonia, 7-9 each with their respective limitations and disadvantages. 1

Snaith-Hamilton Pleasure Scale (SHAPS)
The SHAPS is an instrument used to evaluate the experience of pleasure or the anticipation of a pleasurable experience. It is a self-reporting scale containing 14 items with four response categories: definitely agree, agree, disagree and definitely disagree. Snaith et al. 10 proposed to recode the four categories as dichotomous (definitely agree or agree = 0; disagree or definitely disagree = 1). The higher the score, the higher the level of anhedonia.

The Hospital Anxiety and Depression Scale (HAD)
The HAD is a reliable instrument for screening anxiety and depression in patients with physical illnesses. It was initially developed for use in patients seen at non-psychiatric services in general hospitals.
The validity of the HAD in Brazilian Portuguese was evaluated in chronic pain patients. 20 The HAD comprises two subscales: one for anxiety and another

Ethical considerations
This study was approved by the local institutional review board (MCO-UFBA, process no. 14/2002) and was carried out in accordance with the Declaration of Helsinki. The researchers guarantee that individuals provided written consent and that the documents will be kept confidential.

Statistical analysis
We first evaluated internal consistency using a classical test theory construct, the Cobranch's alpha.
We also fit item response theory (IRT) logistic models using one (

Sample characteristics
A descriptive analysis of the overall sample (n = 228) revealed that the majority of the participants were male (79.8%). The median age was 57 years (percentiles 25-75: 51.0-62.5), and the participants were predominantly married (72.12%) ( Table 1).

Psychometric properties
Internal consistency, as measured by Cronbach's      criterion and log-likelihood for 1, 2 and 3 PL models are shown in Table 3.

Akaike information criteria (AIC), Bayesian information
The SHAPS showed a significant correlation with HAD-D, suggesting convergent validity of the former with external measures of related constructs. Figure 3 displays a scatterplot for the positive correlation observed (Spearman's ρ = 0.249; S = 1,368,914; p < 0.001).

Discussion
In this study, the SHAPS was translated into Brazilian Portuguese and the validity of the resulting SHAPS-BR was examined in a clinical population. The Brazilian Portuguese version of the scale presented adequate internal consistency, with findings that were similar to those of a previous psychometric study conducted with adolescent participants (Cronbach's alpha = 0.87).
Anhedonia is a behavior pattern that can be applied to all age groups, and our result was compatible with the result of that study. 26 Our findings support the use of the SHAPS-BR as an instrument for measuring anhedonia. Internal consistency was high and items presented overall good performance, whilst a small number of positive answers (n = 3-7) probably compromised the precision of estimates. Also, difficulties were observed for items 3,4 and 12 in the 2 PL and 3 PL IRT models (discrimination and pseudo-guessing).
The person-item map suggests that samples presenting more severe levels of anhedonia could generate more appropriate data for investigating SHAPS-BR items, which overall presented higher thresholds in respect to our sample.
The evaluation of hedonic capacity has been useful for biomarker research in psychiatry and neurology. 4 The SHAPS is an established tool in terms of clinical relevance in adult outpatients with major depressive disorder, as it is able to distinguish severely depressed patients from those with mild to moderate depression. 27 Reduced levels of anhedonia may have been related to reductions in suicidal ideation in treatment-resistant patients from several clinical trials of ketamine with either major depressive disorder or bipolar disorder. 28 Additionally, several studies have demonstrated that the SHAPS is relevant in measuring anhedonia symptomatology in medical settings, such as in patients with Parkinson's disease 19 and schizophrenia 17 ; in liver transplant candidates, a statistically significant relationship between hepatic encephalopathy and anhedonia has been found. 29 Previous versions of the SHAPS, validated in other languages, also demonstrated satisfactory psychometric properties: Dutch, 1 Spanish, 30 Malay, 31 Japanese, 18 German, 17 French, 16 and Italian. 19

Disclosure
No conflicts of interest declared concerning the publication of this article.