The Aging Males' Symptoms (AMS) scale: review of its methodological characteristics

Abstract

Background: The current paper reviews data from different sources to get a closer impression on the psychometric and other methodological characteristics of the Aging Males' Symptoms (AMS) scale gathered recently. The scale was designed and standardized as self-administered scale to (a) to assess symptoms of aging (independent from those which are disease-related) between groups of males under different conditions, (b) to evaluate the severity of symptoms over time, and (c) to measure changes pre- and post androgen replacement therapy. The scale is in widespread use (14 languages).

Method: Original data from different studies in many countries were centrally analysed to evaluate reliability and validity of the AMS.

Results: Reliability measures (consistency and test-retest stability) were found to be good across countries, although the sample size was sometimes small.

Validity: The internal structure of the AMS in healthy and androgen deficient males, and across countries was sufficiently similar to conclude that the scale really measures the same phenomenon. The sub-scores and total score correlations were high (0.8-0.9) but lower among the sub-scales (0.5-0.7). This however suggests that the subscales are not fully independent. The comparison with other scales for aging males or screening instruments for androgen deficiency showed sufficiently good correlations, illustrating a good criterion-oriented validity. The same is true for the comparison with the generic quality-of-life scale SF36 where also high correlation coefficients have been shown. Methodological analyses of a treatment study of symptomatic males with testosterone demonstrated the ability of the AMS scale to measure treatment effect, irrespective of the severity of complaints before therapy. It was also shown that the AMS result can predict the independently generated (physician's) opinion about the individual treatment effect.

Conclusion: The currently available methodological evidence points towards a high quality of the AMS scale to measure and to compare HRQoL of aging males over time or before/after treatment, it suggests a high reliability and high validity as far as the process of construct validation could be pressed ahead yet. But certainly more data will become available, particularly from ongoing clinical studies.

Figure 1

Comparison of the mean AMS total scores before and after testosterone therapy in patients 50 years and older: mean (SD) absolute scores (upper graph) and mean (SD) improvement (lower graph) compared with the baseline score: absolute and (upper column) as percent (%) of the AMS score before therapy (lower column).

Figure 2

Average improvement of symptoms after therapy in four categories of severity at baseline. Improvement of the total score after therapy – expressed as percent(%) of the value before therapy (baseline). Means and standard deviation of the relative improvement are depicted. The severer the symptoms at entry the higher the improvement of complaints/quality of life.

Figure 3

Percentage (%) of patients in the four categories of severity of complaints according to AMS results at two points in time: before therapy with testosterone and 12 weeks later after testosterone treatment. The disturbed frequency distribution of severity before therapy (compared to the standard-left part) went back to the distribution in the "normal" standard population after therapy (right part). The population data came from the standardization of the AMS test [3,5]