Analysis of Health Factors as Predictors for the Functioning of Military Personnel: Study of the Factors That Predict Fitness for Duty and Medical Costs of Soldiers of the Royal Netherlands Army

Military Medicine, Jan 2005 by de Raad, John, Redekop, W Ken

In 1998, the Royal Netherlands Army introduced a new examination system, which is based on the "workload-capability" model, to replace the old system, which focused on diagnosis and was solely based on the detection of diseases and infirmities. In a randomized controlled study, we found that soldiers recruited under the new system displayed a statistically significant higher number of days fit-for-duty and incurred lower medical costs than solders recruited under the old system. To gain a better understanding of the reasons for these differences, we studied the association between these results and information collected about the soldiers. In the course of the study, we collected various types of information about the study participants (e.g., education, deployment). During the study, soldiers were asked to complete a questionnaire twice a year, its content based in part on a periodic occupational health examination questionnaire commonly used in The Netherlands. We found that the following factors influenced fitness for duty and medical consumption: education, injuries, actual operational deployment, and the examination system itself. The superior performance of the new RNLA Basic Medical Requirements (BMEKL) system seems partly attributable to the assessment of the ability to meet the task-specific requirements. The primary mechanism is as yet undiscovered.

Introduction

In November 1998, the Royal Netherlands Army (RNLA) introduced a new medical examination system, the RNLA Basic Medical Requirements (BMEKL),1 to replace the previous system (PULHEEMS: all diseases and infirmities that lead to unfit declaration are subdivided into seven categories: physical capacity, upper limbs, locomotion, hearing, eyesight, emotional and mental state). The new system is based on the "workload-capability" model and focuses on the job requirements, whereas the old system was focused on diagnosis and assessed recruits on the basis of the detection of diseases and infirmities.

From June 1999 to June 2001, we performed a randomized controlled study. We monitored 352 soldiers with fixed term contracts after being randomized, declared fit-for-duty by either of the systems and then trained. The aim was to assess whether there were differences between the two examination systems with regard to their ability to identify suitable recruits. The two examination systems were compared using two outcome measures over a 2-year follow-up period: medical costs and the number of days fit-for-duty.2

Soldiers approved using the new system showed a statistically significant higher number of days fit-for-duty (648 days vs. 612) and incurred significantly lower medical costs (EUR 396 compared with EUR 746) than soldiers approved using the old system. Adjustment for other personal characteristics had no effect on these differences. For this reason, we concluded that the new examination system was able to select better recruits than the old examination system.

In a previous Dutch study, de Kort3 studied the association between the pre-employment examination and attrition as a result of illness and found that a medical examination may have only a small effect on workers. In addition, he stated that such an examination still could be acceptable if the risks of the work are high. Notwithstanding the outcome of de Kort's study, the risks of work in the RNLA can be very high, and the new BMEKL examination system is merely based on the actual job requirements as mentioned above. Therefore, in theory, the new system should lead to a higher suitability than the old PULHEEMS system; in concrete terms, more fitness for duty and lower medical costs. The remaining question now was, does the new medical examination system really influence the worker's achievements, or might there be other factors involved?

Many factors may influence a workers health and achievements without leading to attrition. Their influence may be restricted to a feeling of discomfort, more visits to the doctor, and a longer sick leave, thus influencing both fitness for duty and medical costs without any effect on attrition. Another Dutch study showed that the effects that health risks have on employees are attributed to the way in which the employees experience these health risks.5 For this reason, information about the opinions of the workers might help to explain the variation in outcomes such as days fit-for-duty and medical costs that we observed in our study. In fact, such information was collected during this study by means of a self-completed questionnaire to be completed every 6 months, to gain insight into the respondents' experiences of the (health) risks. The question we wanted to answer was: to what extent can the performance differences between the two examination systems (BMEKL vs. PULHEEMS) be explained by the personal experiences reported by the soldiers?

Materials and Methods

Population and Procedure

Two study groups were set up. Participants in group 1 were examined using the old PULHEEMS system and those in group 2 using the new BMEKL system. Between September 22nd and October 16th 1998, 863 candidates were examined, with randomization ensured by changing the examination system every week (Fig. 1). This eventually led to the formation of two study groups totaling 352 persons (PULHEEMS study group, N = 166; BMEKL study group, N = 186).