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Detection of treatment effect
The results of the first clinical study where the AMS scale was applied as outcome measure for testosterone treatment in patients with androgen deficiency. [ 20 ]
The absolute improvement of symptoms during treatment was 15 scoring points of the AMS in average. This is equivalent to 32% of the baseline score on average.
The relative improvement increases with the degree of severity of symptoms at baseline, what fits the general expectation: 11% relative improvement, 24%, 31%, and 39% improvement in males with little, mild, moderate, and severe complaints at baseline. That means, there was still a positive treatment effect detectable with the AMS scale in men with moderate or even mild symptoms.The next Figure shows the capacity of the AMS scale to detect therapeutic efficiency from another angle: the comparison with norm values of the population [ 5 ]. One can see that the level of complaints in elderly patients before therapy is very much shifted toward higher degree of severity (higher AMS total score).
After 12 weeks of testosterone treatment the frequency distribution of patients with a certain severity of complaints became similar to the distribution in the general population of aging males. This is re-assuring and indicates that comparisons with norm values could be helpful for interpreting results of intervention studies. It is another way to look at therapeutic efficiency with the assistance of the AMS scale.Prediction of expert assessment
The AMS scale was also able to predict the independent judgment of the urologists regarding the therapeutic effect. The treating urologist assessed individually the effectiveness of the hormone treatment in the above mentioned intervention study - without knowledge of the results of the self-administered AMS questionnaire which was only later analysed.
Grouping the urologist's expert opinion regarding treatment efficiency into two categories: effective (very effective and effective) and not effective (little, no or negative effect). Similarly grouped were the AMS results - namely effective (at least 5% improvement) and not effective (less than 5% improvement).
The positive predictive value was 89%, the negative predictive value 59%, sensitivity (correct prediction of a positive assessment by the physician) 96% and specificity (correct prediction of a negative assessment by the physician) 30% [ 20 ].In other words, the change of the AMS score fits well with a positive judgment of the physician concerning therapy efficiency, however predicts not very good a negative therapy assessment of the physician. This means, using the total AMS score as criterion, it would result in a high positive predictive value but a less satisfactory negative predictive value, very high sensitivity but low specificity.
A new publication from another treatment study (2006) basically confirmed the findings. The conclusion of the authors was that the AMS scale showed a convincing ability to measure treatment effects on quality of life across the full range of severity of complaints. Effect modification by other variables at baseline was not observed. In addition, results of the scale could predict the subjective clinical expert opinion on the treatment efficiency.
[5]. Heinemann LAJ, Zimmermann T, Vermeulen A, Thiel C. A New 'Aging Male's Symptoms' (AMS) Rating Scale. The Aging Male 1999; 2:105-114.
[20]. Moore C, Huebler D, Zimmermann T, Heinemann LAJ, Saad F, and Do Minh T. The AMS scale as outcome measure for treatment of androgen deficiency. Eur Urology 2004 ; in press.
