Explaining Medical Model Exceptions - Computational Intelligence in Healthcare: Advanced Methodologies - page 262

2.2.3 Solving the Problem “What in the Patient's Condition Improved?“
There are at least two criteria to select factors for the model. First, a factor has to be
significant, and second there must be enough patients for which this factor was meas-
ured at least for six months. So, some principally important factors were initially not
taken into account because of missing data. The list of solutions includes these factors
(figure 3): haemoglobin and maximal power (watt) achieved during control training.
Oxygen pulse and oxygen uptake were measured in two different situations, namely
during the training and before training in a state of rest. Therefore we have two pairs
of factors: oxygen pulse in state of rest (O2PR) and during training (O2PT), maximal
oxygen uptake in state of rest (MUO2R) and during training (MUO2T). Measure-
ments made in a state of rest are more indicative and significant than those made dur-
ing training. Unfortunately, most measurements were made during training. Only for
some patients did corresponding measurements in a state of rest exist. Therefore
O2PT and MUO2T were accepted as main factors and were incorporated into the
model. On the other side, O2PR and MUO2R are solutions for the current problem
“What in the patient's condition improved?”
In the case base every patient is represented by a set of cases, and every case repre-
sents a specific problem. This means that a patient is described from different points
of view, and accordingly different keywords are used for retrieval.

2.3 Another Problem

Just one of many problems that can arise based on the observed data set and that can
be solved and analysed by the dialogue (figure 3) is described above. Another inter-
esting research question is “Does it make sense to begin with the fitness program dur-
ing the first year of dialysis?” The question arises, because the conditions of the pa-
tients are considered to be unstable during their first year of dialysis. So, the question
is expressed in this way “When should patients begin with the fitness program, earlier
or later?” The term “earlier” is defined as “during the first year of dialysis”. The term
“later” means after at least one year of dialysis. To answer this question two groups of
active patients are considered, namely those who began their training within the first
year of dialysis and those who began it later (table 2).
According to Fisher's exact test dependence can be observed, with p < 0.05. How-
ever, the result is not as it was initially expected. Since patients are considered as un-
stable during their first year of dialysis, the assumption was that an earlier beginning
might worsen the conditions of the patients. But the test revealed that the conditions
of active patients who began with their fitness program within the first year of dialysis
improved even more than the conditions of patients starting later.

Table 2. Changed conditions for active patients

Earlier Later

Better 18 10

Worse 6 16