Chapter 5 AN ONTOLOGY FOR TB ADHERENCE FACTORS
5.1 Overview of the Ontology
5.1.3 Key Relationships in the TB Adherence Factors Ontology
The Place class is also extended to include socio-economic properties than can be used to describe the characteristics of the study location (see Figure 5.4). This allows for users to search for a place of interest using the characteristics as a guide. Some of the data properties that were included are the economic classification, population characteristics and spatial information. Also included are hasTBprevalence, and hasHIVprevalence data properties to describe the prevalence of TB and HIV/AIDS in various places or locations.
5.1.2.5 The Interdependency
The Interdependency class is used to represent a finding of interdependency between factors.
Suppose, for example, a scientific publication finds the following: “Being male is a negative influencing factor that is influenced by the unfavourable working conditions that most males experience at work.” This would indicate a causal relationship between gender-related influencing factors and working condition.
Representing interdependency as a class provides the possibility of relating it to the evidence (studies) that asserts (finds) the existence of any interdependency. It also allows for multiple dependency relationships between influencing factors and different interdependencies found in different studies.
The key concepts are linked by relationships between the classes. There are 5 major object properties that define relationships: assertsInfFactor, hasInfFactor, isDocumentedAs, assertsInterdependency, isCarriedOutAt.
5.1.3.1 Evidence-TABInfluencingFactor
An assertion relationship exists between Evidence and TABInfluencingFactor and is defined as assertInfluenceFactor object-property. The assertion relationship that exists between the two classes is defined as follows: “a subject is asserted as an influencing factor with a specific influence characteristic by one or more evidence”. The relationship defines an influencing factor’s existence as asserted by some evidence, e.g. a published study. An Evidence is independent of TABInfluencingFactor but TABInfluencingFactor is dependent on Evidence. This implies that a TABInfluencingFactor only exists as a factor in the ontology if it is asserted by at least one Evidence.
The assertInfluenceFactor object-property has sub-properties that qualify the type of influence that is asserted (see Table 5.2). The properties are designed in hierarchical form with the main property being the generic assertion of influencing factor. There is a total of six sub- properties, three influence types and three influence periods. These are based on the dimensions identified in previous steps from the existing models [1] [28] [40] [39]. The influence type dimension was classified into two categories: positive and negative [1] which were similar to the increment and decrement influence respectively [28].The third influence type category is the “no effect” as identified by [28], and is termed a “neutral” influence type. The development of the period of influence was based on the treatment phases identified by [40] and [39].
Asserts influence factor property
Influence Type Asserts positive influence factor Asserts negative influence factor Asserts neutral influence factor
Influence Period Asserts intensive phase influencing factor Asserts continuous phase factor
Asserts drug-resistance phase factor
Table 5.2: TB adherence influencing factor’s property types and periods
The different assertInfluenceFactor sub-properties are described below:
Influence Type
o assertPositiveInfluenceFactor: The property states that the Evidence confirms a significant positive TABInfluencingfactor. Positive influence implies that the factor motivates good adherence behaviour.
o assertNegativeInfluenceFactor: The property states that the Evidence confirms a significant negative TABInfluencingfactor. Negative influence implies that the factor motivates poor adherence.
o assertNeutralInfluenceFactor: The property states that the Evidence confirms a neutral TABInfluencingfactor. Neutral influence implies a non-significant or unknown influence of the factor.
Influence Period
o assertIntensivePhaseFactor: The property states that the Evidence confirms that a TABInfluencingfactor is influential at intensive phase.
o assertContinuationPhaseFactor: The property states that the Evidence confirms that a TABInfluencingfactor is influential at the continuation phase.
o assertDrugResistancePhaseFactor: The property states that the Evidence confirms that a TABInfluencingfactor is influential at drug resistance phase.
It is to be noted that the use of the specific sub-property is not compulsory, i.e. the assertInfluenceFactor property may still be used if the user does not wish to qualify the influence of a factor.
5.1.3.2 Evidence-Work
The relationship between Evidence and Work associates an evidence with its documentation in a publication repository. It links evidence that was reported in a Work with its documentation.
This relationship strengthens the reliability of the evidence in order to guide users in the selection of influencing factors. This is useful for ClinicalStudyEvidence published as Work in various forms of expression, such as journals and conference proceedings. It, in turn, builds more confidence in influencing factors asserted by the Evidence.
The relationship is denoted by isDocumentedAs object-property. It shows whether a ClinicalStudyEvidence is specific or/and has been published as a research output. This relationship allows users to discover the influencing factors that are supported by published studies. The Work also serves as a reference for factors discovered in specific studies.
5.1.3.3 Evidence-Place
The isAtRegion property depicts the relationship between the Evidence and Place classes.
The relationship indicates the location of the Evidence, for instance the community of the cohort or survey study population. All Evidence must have only one location for consistency of the information. An item of evidence is valid only for the place to which it is related. However, several items of evidence may be related to a single place.
The relation is very important since it can be used to find specific factors that are prevalent within a particular region. The isCarriedOutAt property is a sub-property of the isAtRegion which is specific to ExperimentalEvidence. This indicates the location (town, region or country) where the experiment is carried out.
5.1.3.4 Evidence-Interdependency
The assertInterdependency relation is used to represent the relationship between the Evidence and Interdependency classes and it defines the existence of interdependency between influencing factors, as asserted by one or more items of evidence. An evidence asserts the existence of interdependency between certain factors and the assertInterdependency property facilitates this association.
5.1.3.5 Interdependency-TABInfluencingFactor
The relationship between the Interdependency and TABInfluencingFactor classes points to the factors that depend on one another. It defines an influencing factor as either a dependent or an independent factor in an interdependency relationship that has been asserted by evidence.
The relationship is represented by hasInfluenceFactor object-property. There are two sub- properties, hasDependentFactor and hasIndependentFactor. The hasIndependentFactor indicates factors that influence other factors and the hasDependentFactor indicates factors that are influenced by other factors in an Interdependency class.