What results should be used to measure whether a drug is a “good” drug? Improve survival rate? Improve work ability? Few side effects? Are you capable of returning to work? To attend your daughter’s wedding alive? all of the above?
Usually, health economists measure the value of a treatment to ordinary people. Preferences for efficacy, safety, dosage, and other factors are averaged across the population. However, can we really measure whether a treatment helps more people achieve their personalized goals?
This is the specific goal of the Goal Achievement Scale (GAS).As mentioned in Zaza et al. (1999), The GAS method relies on six main steps.
1. Selection of target area. Evaluate the patient’s problem areas and determine a set of priority target areas (usually 3-5). The identified goals should be those that will be the focus of the care plan or intervention-patients may have many problems that are not expected to change, or that are not related to a particular treatment plan. As a general rule, the guide should have at least three goals.32
If new goals are determined during the treatment, these goals can be added.
2.Weights. As an optional step, a subjective weight can be assigned to the target area to reflect its estimated relative importance. The weight of the target area may be clinically helpful, but if not, this step can usually be omitted without significant impact on the GAS score.
3.Follow-up time selection. Determine the expected time frame for achieving the goal. This is usually the same for all goals, but may vary for each goal.
4.Statement of Expected Resultss. If treatments and interventions are effectively implemented, the most likely expected result will be recorded as a “0” category in the center of the follow-up guidelines. The level of achievement should be descriptive, observable, and objective-independent evaluators should be able to reliably assess the patient’s level of achievement for each goal. The words “change” or related terms such as “better” or “improvement” should be avoided to support the description of the observable state. Although it may be tempting to use GAS to measure activities, workloads, or care processes, GAS is best used to measure results rather than specific procedures or processes used to achieve results. Therefore, avoid “process goals” such as “schedule a CT scan.”
5.Complete other scale levels. Fill in the remaining scale levels for each target area. These indicate that the possible results are much lower than expected (-2), slightly lower than expected (-1), slightly better than expected (+1) and far better than expected (+2). As with the expected results determined in step 4, these will be objective and observable indicators of the patient’s status in each target area. The goal should clearly be scored on only one level. As with any scale, target levels should not overlap. If it is difficult to imagine a better result than the expected (“0”) level, the “+1” and “+2” levels may be scaled to reach the same expected level, but with shorter time or fewer resources. A standardized scoring scale may help provide scale-level descriptors.
6.follow up. At the end of the follow-up period, the patient is evaluated according to the level of goal achievement, and her or his status is marked on the follow-up guide. The follow-up status is usually marked with an asterisk, and the initial evaluation level is marked with a check.
Using this method, the individual’s final goal achievement score can be calculated as follows:
Here, the term wattI Is the weight assigned to IThe first goal, and XI Is the value that reaches the level IThe first goal.the value of XI The range is between -2 and +2.If the weights of all targets are equal, then wattI=1. Generally speaking, a score of 50 or higher means that the patient has reached their goal on average.
Although GAS can be used to measure the value of various interventions, Zaza et al. (1999) The article provides examples of individuals with pain, including cancer pain, elderly pain, pediatric pain, and work-related non-malignant pain.
A systematic literature review of GAS Gaasterland et al. (2016) Fifty-eight articles using GAS were identified, of which 38 were drug studies that used GAS as an outcome measure, and 20 studies used GAS in other (ie, non-pharmaceutical) environments. Although GAS is an attractive method of measuring the impact of drugs due to the personalized nature of drugs, more research is needed to determine how to best implement GAS. E.g, Tennant (2007) Note that using an ordinal rather than a linear scale may be more suitable for identifying the smallest clinically important difference (MCID) in the results.