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The sole purpose of the "English Kinda Thing" is to document my attempts to correct my own mistakes in standard English usage and to share the resources I find. In no way do I attempt to teach nobody English through these blurbs--just as I intend not to teach nobody to be a neurotic and psychotic handicap in Ratology Reloaded or Down with Meds! :-)

Monday, June 8, 2009

Self-Report Scales and Procedures for Assessing Pain in Adults (Jensen & Karoly, 2001)

Jensen, M. P., & Karoly, P. (2001). Self-Report Scales and Procedures for Assessing Pain in Adults. In D. C. Turk & R. Melzack (Eds.), Handbook of Pain Assessment (2 ed.). New York: The Guilford Press.

Self-Report Scales and Procedures for Assessing Pain in Adults (Jensen & Karoly, 2001)
In this chapter, the authors adopted the pain context model within which pain is considered as a latent construct, similar to depression or anxiety that cannot be observed directly and can only be inferred. At the same time, when it comes to the measurement of latent constructs, all too often, even the best measures or indicators might not be closely related. It is because the components of the same construct might not always occur synchronously or in the same configuration.

For instance, some people might report pain but not manifest non-verbal pain behavior; other people might manifest non-verbal pain behavior but do not report pain; still others might show non-verbal pain behavior and report pain at the same time.

Due to the multidimensional nature of pain, we have to identify the relevant dimensions before we could proceed with its measurement. Despite the discrepancies among the different measures available in the market, four dimensions are currently assessed in all patients including the intensity (e.g., 7 on a 10 point scale), affect (e.g., distress), quality (e.g., dull, sharp) and location (e.g., cervical, lumbar, finger) of pain. Among these four dimensions, pain affect is possibly more complex than the rest. It is because pain affect is a mental state triggered by the individual appraisal of the threat; it, thus, could be manifested as a heterogeneous group of emotional reactions.

Assessing pain intensity

Most of measures of pain intensity are highly correlated with the others

Verbal Rating Scales (VRSs)

Patients are given a list of adjectives describing pain. They are supposed to rank the adjectives based on pain severity and assign each with a score. For instance, 0 indicating no pain, 1 indicating mild pain, 2 indicating moderate pain and 3, severe pain.

Cross-modality matching procedure has been used to transform VRS ratings to ratings involving other modalities that are more likely to have ratio properties (e.g., loudness of a tone).

The problems of VRS

  1. Time consuming

  2. Standardized scores are developed using non-patients in reaction to experimental pain while it has been found that patient with chronic pain might rate the adjectives differently from those sustaining acute pain

VRSs have demonstrated their validity based on the high correlation they have with other pain intensity measures. They also demonstrate their sensitivity to treatment having substantial impacts on pain intensity.

The problem was VRSs is that patients need to be familiar with the list of adjectives, the task is time-consuming and it is difficult to tell the level of understanding the patients have with listing. Sometimes, patients might not be able to find an adjective to describe their condition. In addition, the VRSs are found to be less reliable for illiterate patients.

Visual Analogues Scales (VASs)

A VAS consist of a line with one end indicating “no pain” and the other end indicating “Pain as bad as it could be” When a VAS have points and labels associated with these points, it is called a graphic rating scale (GRS). Existing research has substantiated the validity of the VASs through studies measuring the association between pain intensity and pain behavior, sensitivity to treatment effects and how distinct the scale is from other components of pains. In addition, VASs have been found to be more sensitive to changes especially when comparing to scales with limited response category.

An alternative version of VASs was designed to counteract the issue of scoring complexity. With the mechanical VAS, participants use a sliding marker on one side of a paper or plastic to provide their responses while the researchers use the other side of the paper or plastic to get the intensity score. Mechanical VASs have been found to correlate highly with paper-and-pencil VASs and has good test-retest reliability within a two-hour window.

The VASs also have various drawbacks. For instance, participants need to have a minimal level of motor ability as well as a certain level of cognitive ability. For people with cognitive difficulties, the use of VAS is not suggested.

Numerical Rating Scale (NRS)

With NRS, patients are simply asked to rate their pain experiences based on either a scale of 0 to 10, 0 to 20, or, 0 to 100 with 0 indicating no pain and 10, 20 or 100 indicating the worst level of pain possible. While NRS could be done verbally, it is also available in paper and pencil format.
The validity of NRS has been well-documented. They correlate well with other measures of pain intensity. They are sensitive to treatment effect. It can be used on a greater range of patients.
The weakness of NRS is that it does not have the quality of a ratio scale. In other words, when a patient’s rating drop from 9 to 6, it doesn’t mean that the intensity of pain has decreased by 33%.

Picture of Face Scale

With this method, each person has shown pictures and is asked to indicate which one of the pictures best represent their experiences with pain while each picture is associate with a score. This scale is great for patients who might be illiterate. Yet, the pictures still need to be explained to patients when might be cognitively impaired or who might be young children.

Descriptor Differential Scale of Pain Intensity (DDS-I)

DDS-I contains a list of adjectives describing levels of pain intensity. Patients are asked to rate whether their experience is more or less than what is described in the word.
DDS-I has high internal consistency as well as test-retest stability. It also correlate highly with other pain intensity measure and is sensitive to changes in the state including treatment effect and experimental stimulation. The DDS-I also has the quality of ratio scale.

One major drawback of DDS-I is that it is too complex and time consuming.

Assessing pain affect

Pain intensity could be defined as how much one hurts; pain affect is defined as “the emotional arousal and disruption engendered by the pain experience. Pain affect has been considered as a multidimensional construct with the dimensions either correlated or uncorrelated. However, to date, there exists no multidimensional measure of pain affect. Overall, there are 5 general methods of pain affect assessment: The affective subscale of the McGill Pain Questionnaire (MPQ), the Verbal Rating Scales (VRSs), the Visual Analogues Scales (VASs), the Descriptor Differential Scale of Pain Affect (DDS-A) and the Affective Scale of the Pain-O-Meter (POM).

Verbal Rating Scales (VRSs)

VRSs for pain affect consist of descriptors for increased discomfort and suffering (e.g., bearable, excruciating). They are scored in three ways: ranking, cross-modality matching or standardized score method. There are mixed findings in the validity of VRSs. On one hand, when used to evaluate treatments designed to impact the emotional component of pain, VRSs have been found to be more sensitive than pain intensity. However, various studies found that pain affect and pain intensity are very often overlapped; in other words, while pain affect and pain intensity might be two distinct constructs, they are not completely independent from the others and, actually, the interdependence might be needed.

Visual Analogues Scales (VASs)

The extremes response used in VAS affect measure could be “not bad at all” and “the most unpleasant feeling for me.” In terms of the validity of VASs, VASs affect measures seem to be sensitive to treatment effect and more sensitive to treatment than that of intensity as well. In addition, they have the quality of ratio scale. Unfortunately, VASs affect scale doesn’t discriminate from the intensity measure and most of the research was done on younger populations (as opposed to the older adults). Because VASs affect measures are single item scales, they might be less reliable and valid when comparing to measures containing multiple items and examining a full range of responses. No studies have been done, though, to compare the VAS affect measure that that of others.

Descriptor Differential Scale of Pain Affect (DDS-A)

DDS-A is a multi-item scale and provides more reliable and valid assessment than single-item scales such as VASs. Existing research has also demonstrated its test-retest reliability and internal consistency. A special merit of DDS-A is that respondents could not only indicate whether their affect response is higher or lower than the descriptor as well as by how much more.

Affective Scale of the Pain-O-Meter (POM)

The POM includes a VAS and two lists of 11 pain descriptor selected from MPQ. Patients indicate which of the 11 descriptors describe their experience as well as the intensity value. Although the scale has been found to be reliable and demonstrate the ability to discriminate between patients of different disorders. There is still a need for scale validation.

Questions to be answered:

  1. Global measure or separate indices?

  2. Are single-item measure less reliable than multi-item measure?

Assessing pain Quality

  1. The sensory scale from the McGill Pain Questionnaire (MPQ)

  2. The Neuropathic Pain Scale (NPS)


Patients are requested to rate the severity of the pain descriptors with 0 indicating “no pain” and 10 “the most intense pain sensation imaginable). The NPS also allow the patients to indicate the fluctuation of the pain over time. Because many of the indicators seem to correlate poorly, it has been suggested that the use of a composite score might have limited meaning and a profiling approach might yield more meaningful information. On the other hand, the NPS has been developed to assess neuropathic pain, it might be less meaningful for other types of pain conditions.

Assessing Pain Location

  1. Line drawing to present the localized pain

  2. Shading areas

  3. Symbols to represent different pains
    o Internal "I" or external "E"
    o Numbness "--"
    o Pins and needles “oo”
    o Burning pain “xx”
    o Stabbing pain “//”

The correlation between lower back pain and interferences with life’s activities


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