1. General information

A total of forty-one people were selected to take part in the study. All were rehabilitation patients who were admitted to Dongguan Rehabilitation Hospital for various treatments from March the 1st to June the 30th, 2024, at the Department of Bone and Joint Rehabilitation and the Neurological Rehabilitation Center. The criteria excluded patients suffering from cognitive impairment, aphasia, and other understanding and speech communication disorders.

2. Evaluation methods

The pain research team used both FPS-R and POFM to evaluate the patients’ level of pain (Fig. 1, 2).

FPS-R uses six different facial expressions, ranging from very happy (smiling) to very sad (crying). Face 0 means no pain, and face 10 means the most pain imaginable. These six facial makeup expressions correspond to pleasure, discomfort, mild pain, pain, severe pain, and unbearable pain respectively, and are consistent with pain rating scales 0, 2, 4, 6, 8, and 10.

The primary goal for creating the Wong-Baker FACES® Pain Rating Scale was to help children effectively communicate about their pain so staff and parents could more successfully manage their pain. Initially, the numbers 0–5 were used to quantify the pain, but using the numbers 0–2–4–6–8–10 avoids confusion as it is more consistent with the numeric rating scale of 0–10 [17].

During the assessment, patients are asked to choose the face which best expresses their level of pain, using the numbers 0–2–4–6–8–10, consistent with Wong Baker FPS-R.

POFM also uses six pictures. The faces of the characters are outlined in specific patterns, representing different historical figures in the opera. The facial lines of POFM range from thin to thick; the colors from pink to black and red; and the expressions from gentle and happy, to angry and painful. The expressions of the six POFM characters correspond to six scales from 0 (painless) to 10 (most serious pain). During the pain assessment, the patient is asked to choose which POFM image best expresses the degree of pain.

In this study, the pain assessment patients were between 27 and 76 years old, with an average age of 41.2 years. There were thirty-one male patients and ten female patients, as shown in Fig. 2. The patients had various causes of pain, including twenty-nine fractures, five shoulder pain from stroke, four hand traumas, one cervical spondylosis, one lumbar disc herniation, and one knee joint effusion, as shown in Fig. 3.

3. Statistical analysis

SPSS 27.0 statistical software was used to perform a paired t-test on the two pain scoring methods. The measurement data were expressed as X + S. The paired t-test was used for comparison between groups, and p < 0.05 was considered statistically significant.

A total of forty-one patients participated in the study, the aim of which was to compare the results of the Wong-Baker FPS-R and the POFM pain assessment methods. A paired t-test was performed on the two assessment methods by SSPS 27 statistical software. The results of the two evaluation methods in patients with pain are shown in the Tables 1, 2.

The results showed that the standard deviation of the first assessment method (Wong – Baker FPS-R) was 1.724, and the mean standard error was 0.269. The standard deviation of the second evaluation method (POFM) was 1.534, and the standard error was 0.240. The t-value measured by the paired t-test was 1.817, and the p-value was 0.77. According to the test level of α = 0.05, there is no statistical difference between the results of the two methods, and the results of the two evaluation methods are consistent, as shown in Table 3.

The different types of pain assessment scales currently used in clinical practice in China are translated into Chinese from English versions of scales used in European and American countries. However, the differences between Chinese and Western cultures, languages, habits, and medical systems, cause errors in the translation process, which directly affect the accuracy of pain assessment results and bring misjudgment to effective treatment [7][11].

The pain measurement methods developed using samples may only come from one country, and / or from different cultures (for example, Western or Eastern); however, people from different cultural backgrounds speaking different languages may experience different forms of pain, and have different experiences and descriptions of pain [8]. This possible variability is of great significance for evaluating the effectiveness of pain quality measures, which are directly translated into different languages without cultural adaptation. The measurement method developed using patient samples from one country or cultural background, directly translated into one's own language for use, may not necessarily be suitable for evaluating pain quality in other countries or cultures [12].

One disadvantage of FPS-R is that subjects (patients) need to carefully observe and identify cartoon expressions before evaluation [16]. Because patients’ pain levels are measured through selection of an image of a facial expression, the evaluation results are affected by cultural and other interference factors [13]. It is worth mentioning that the score of FPS-R is a categorical variable (an integer score of 0 to 10), and there are eleven levels of evaluation, so it can be statistically tested by parameters.

Chinese people of all ages are very familiar with POFM expressions, so find them easy to identify [14]. This study selected six POFM expressions to assess patients’ levels of pain. The six expressions correspond to pleasure, discomfort, slight pain, pain, severe pain, and unbearable pain respectively, and are consistent with the pain score scale 0, 2, 4, 6, 8, 10. When using POFM to evaluate pain, the patient selects the POFM expression which best corresponds to the degree of pain they are experiencing, and the assessor records the selection in terms of the scale value of the pain score.

In this study, the main forms of patient pain were limb pain caused by fracture, and shoulder pain caused by stroke hemiplegia. In some patients, pain was caused by hand trauma, cervical spondylosis, and localised pain by lumbar disc herniation.

The research results indicate that for Chinese patients, POFM is a sufficiently valid tool for pain measurement, with significant correlations with another commonly-used internationally-recognized pain scale, Wong – Baker FPS-R.

There were a few limitations to the study. Firstly, patients’ preferences of the pain assessment scales were not evaluated. Also, the utility of POFM was only tested in a specific pain model, such as limb pain caused by fractures, and shoulder pain caused by stroke hemiplegia; therefore, the results cannot be generalized for all pain conditions within a given population. Before the formal use of various functional pain assessment scales is adopted in clinical practice, more in-depth research into the reliability, validity, and sensitivity of the scales needs to be carried out [15].

We provided additional support for the effectiveness of the POFM scale in assessing the severity of pain in rehabilitation patients. Our conclusion is that the POFM scale is a suitable tool, even for patients with low educational levels, as it is easy to use, easy to understand, and does not require reading or writing skills, making it particularly suitable for Chinese patients. The first author of this article declares that there is no potential conflict of interest. The research funding comes from the author's own source.

Conflict of Interest:The authors declare no apparent or potential conflicts of interest related to the publication of this article.

Funding:The authors declare no external funding for this study.

Author Contributions:

Study concept and design – Wang Xiao-Jun

Data collection and processing: Gao Shan-Qu, Chen Chun-Lan, Zhang Jian-Fen, Zhu Yan-Ning, Huang Jing-Han

Statistical processing: Han Xin-Yi, Cai Zhi-Chon

Writing: Wang Xiao-Jun, Carly Tinkler

Editing: Wang Xiao-Jun

Конфликт интересов: авторы декларируют отсутствие явных и потенциальных конфликтов интересов, связанных с публикацией настоящей статьи.

Источник финансирования: авторы заявляют об отсутствии внешнего финансирования при проведении исследования.

Участие авторов:

Концепция и дизайн – Ванг Сяо-Цзюнь

Сбор и обработка материала – Гао Шань-Цюй, Чен Чунь-Лань, Жанг Жань-Фэнь, Жу Янь-Нин, Хуанг Жин-Хань

Статистическая обработка – Хан Синь-И, Цай Чжи-Чон

Написание текста – Ванг Сяо-Цзюнь, Тинклер Карли

Редактирование – Ванг Сяо-Цзюнь