Judging the Neonatal Abstinence Syndrome Assessment Tools to Guide Future Tool Development: The use of Clinimetrics as Opposed to Psychometrics

Abstract

In the face of the current Neonatal Abstinence Syndrome (NAS) epidemic, there is considerable variability in the assessment and management of infants with NAS. In this manuscript, we particularly focus on NAS assessment, with special attention given to the popular Finnegan Neonatal Abstinence Score (FNAS). A major instigator of the problem of variable practices is that multiple modified versions of the FNAS exist and continue to be proposed, including shortened versions. Furthermore, the validity of such assessment tools has been questioned, and as a result, the need for better tools has been suggested. The ultimate purpose of this manuscript, therefore, is to increase researchers' and clinicians' understanding on how to judge the usefulness of NAS assessment tools in order to guide future tool development and to reduce variable practices. In short, we suggest that judgment of NAS assessment tools should be made on a clinimetrics viewpoint as opposed to psychometrically. We provide examples, address multiple issues that must be considered, and discuss future tool development. Furthermore, we urge researchers and clinicians to come together, utilizing their knowledge and experience, to assess the utility and practicality of existing assessment tools and to determine if one or more new or modified tools are needed with the goal of increased agreement on the assessment of NAS in practice.

Keywords: Finnegan Neonatal Abstinence Score; Neonatal Abstinence Syndrome Score; formative model; predictive accuracy; reflective model.

Figure 1

Visual and mathematical representations of a generic psychometrics-based reflective model in which items X₁, X₂, and X₃ are caused by and hence are reflections of the hypothetical construct θ. Each item has its own equation in which the influence of θ is denoted by λ, and the items may have measurement error, e. The items are expected to be strongly correlated due to the influence θ has on each one. Note that the number of items is not restricted, and a scenario with three items was chosen for simplicity.

Figure 2

Visual and mathematical representations of a psychometrics-based reflective model in which crying, general convulsions (GC), mottling, etc. are caused by and hence are reflections of neonatal abstinence syndrome (NAS). Each symptom has its own equation in which the influence of NAS is denoted by λ, and the symptoms may have measurement error, e. The symptoms are expected to be strongly correlated due to the influence NAS has on each one.

Figure 3

Visual and mathematical representations of a generic clinimetrics-based formative model in which items X₁, X₂, and X₃ combine to form the true hypothetical construct θ_True. The disturbance term represents the influence of all other factors besides X₁, X₂, and X₃ on θ_True. The numerical weights applied to the items in the assessment tool are represented by b₁, b₂, and b₃. Note that the number of items is not restricted, and a scenario with three items was chosen for simplicity.

Figure 4

Visual and mathematical representations of a clinimetrics-based formative model in which crying (EC, excessive crying; CC, continuous crying), general convulsions (GC), mottling (M), etc. combine to form Neonatal Abstinence Syndrome (NAS) severity. The disturbance term represents the influence of all factors not accounted for by the given assessment tool. The numerical weights applied to the corresponding items in the assessment tool are represented by b_EC, b_CC, b_GC, and b_M. In the visual representation, b_C is equivalent to either b_EC or b_CC, depending on the severity of crying.