Situational Pain Scale (SPS) - Instructions

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  1. Downloading test packages
  2. Administering the questionnaire
  3. Analysing the subject's responses
  4. Interpreting the pain representation measures

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Downloading test packages

The test packages for administrating the SPS is available for download to registered users. Registration is FREE and will only take a few minutes to complete. The test packages are available in two languages (English and French).

Each package contains the instruction sheet and the 10 scoring sheets (10 different random orders).

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Administering the questionnaire

scoring sheet 3 [+] Figure 1: SPS scoring sheet

The SPS is administered as a self-report questionnaire. Subjects do not experience the painful situations, they are asked to imagine them and to estimate the pain intensity of each situation.

The activities are presented in a random order to avoid any systematic effect. Ten different random orders of presentation are used. The evaluator selects the next one of the 10 orders for each new assessment, no matter which patient is tested.
During the evaluation, a 4-level response scale is presented to the patients. Patients are asked to rate their perception on the response scale as ‘not painful’, ‘slightly painful’, ‘moderately painful’, and ‘extremely painful’. Subjects have the opportunity to rate situations as ‘impossible to estimate’.

The scores are entered as shown in the Figure 1.

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Analysing the subject's responses

Subject’s responses to the questionnaires can be submitted for an online analysis analysis on this web site.
The analysis is based on the Rasch model and allows raw scores to be converted into linear measures of ability. The conversion can be done even if the subject answers only part of the items (the patient's responses to some items are missing). Ten data input forms are available in the same order as the paper testing forms. Select the order of items (1 to 10) used to evaluate the patient and enter the responses on the online form. Submit the responses for an online analysis of the subject responses and the subject’s ordinal score to the questionnaire will be converted into a linear measure of the subject’s pain representation.

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Interpreting the pain representation measures

Figure 2:SPS evaluation report [+] Figure 2: SPS evaluation report

The evaluation report is presented in Figure 2. The subject’s pain representation (vertical red line) and its 95% confidence interval (dotted red lines) are located on the pain representation scale (abscissa) expressed in logits. The higher the pain representation of a subject the more the measure will be located to the right. The logit is a linear unit that expresses the ratio of the probability of rating a given situation in one category to the probability of rating the same situation in the category just below. The pain representation scale is centred on the average item difficulty (0 logit).

The items are listed from top to bottom by decreasing difficulty order. The item map shows the most probable score (0 = ‘not painful’, 1 = ‘slightly painful’, 2 = ‘moderately painful’ and 3 = ‘extremely painful’) to each item as a function of the pain representation of the subject and the painfulness of the item. Note that ‘I get my fingers caught in the car door' is the most painful item; ‘My lips are chapped’ is the easiest. Note also that the most probable score for any given item increases with the subject’s pain representation.

The sigmoïd curve shown at the bottom relates the total score on the questionnaire to the pain representation measure (for a complete response set). Note that the score increases with pain representation, although the increase is not linear given the shape of the curve. Therefore changes of pain representation must be interpreted in linear logit units rather than in raw scores.

The subject’s response to each item is circled (missing responses are not shown). For any particular item, the range overlapping the 95% confidence interval indicates the most probable score(s) given the overall pain representation measure. Note that in the example, most scores fit with the overall pain representation measure of the subject indicating the subject scores are coherent across items. The item ‘I get a speck of dust in the eye’ is scored as 'not painful' while it is expected to be more painful, given the overall pain representation measure. The item ‘I bite my tongue' is scored as 'extremely painful' while it is expected to be less painful, given the overall pain representation measure. These unexpected scores may help you to diagnose an atypical behaviour of the subject.

The evaluation report also indicates the pain representation measure of the subject on the scale and the standard error of measurement (in logits). Keep those in your records in order to measure the subject evolution at a future occasion.

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