This study is among the first investigations of health promotion interventions in the maritime work place. Work place health promotion in general, has often proved to be challenging , but the maritime setting seems even more demanding than most. According to two systematic reviews, typical, worksite intervention studies have reported participation rates as low as 8-10% and as high as 64-97% with a median of 33-61% [23–25]. Rates for the present study were above the lower limit and – at least in comparison to one of the systematic reviews – above the reported median. Initial interest in participation in the different intervention offers varied between around 30-50%. Only the semi-mandatory cooking courses reached a rate of 75%. This might partly reflect a general lack of motivation or prioritization of health issues among seafarers or a reluctance to deal with these issues in the work place (see below), which suggests that considerably more efforts at motivating this target group for health promotion and marketing such interventions might be called for. However, it also became clear that actual reach was still considerably below the initial rates, and a main factor for this seems to lie in the nature of the work. Seafarers and their work places literally are “moving targets” where not only the work places (the ships) travel, but seafarers also frequently shift between ships and all move from ships to their homes which are widely dispersed which creates fundamental different changes from “normal”, land-based WHP. Providing interventions for such a target group is a distinct logistic challenge which might require resources beyond the level of what can be expected to be needed for a “normal” stationary work place.
Changes in health behaviors and health indicators
As for percentage of smokers among employees, only a slight and non-significant decrease of 2% occurred between both measurement points. Considering that between 2008 and 2009 a 7% reduction of daily smokers was registered among men from the general Danish population aged 20–69 years, seafarers not only had higher smoking rates than the general male population [26, 27], but also seemed to be lagging behind the downward secular trend It should be noted, however, that such a comparison is necessarily tentative since possible differences in educational and occupational backgrounds between the two samples cannot be accounted for. A significant positive effect was found for the smoking cessation intervention, which, however, should be interpreted with caution, as only few seafarers had signed up for the course. While for many non-participants logistic issues seemed to have played a major role for not feeling able to attend, it must also be assumed that the few who actually did attend differed substantially in motivation and determination from those who did not. However, it also needs to be noted that the finding is in line with results from a Cochrane review of onshore workplace interventions for smoking cessation . Cahill et al.  found strong evidence that individual workplace cessation interventions as well as group counseling and pharmacological treatment to overcome nicotine addiction significantly increased the likelihood of quitting smoking. Despite its methodological limitations the present study indicates that a smoking cessation intervention in the maritime workplace setting has the potential to make a significant contribution to seafarers’ health. To achieve more broad-based success, a more specified and tailored approach is required which takes into account the specific restrictions inherent in a “moving work place”. Instead of trying to schedule joint dates for crew members from different ships, which seems non-feasible, it might be tried to target smokers within their ship crews in order to ensure some continuity of group counseling and also enable daily group support by offering sessions compatible with arrival or departure times in/from port, by sending out counselors to the ships while in port or during crew change at sea and/or by offering internet-based support.
Even though slight improvements on exercise level were noted, these changes were not significant, whereas there was a significant increase in physical fitness scores showing that 1/3 of the participants had improved their fitness score at T2 towards the recommended level. One explanation for this seeming discrepancy might be a difference in samples, since the fitness scores could only be computed for the smaller – and probably more motivated – subsample, which had not only participated in the questionnaire survey but also in the health profile at baseline and follow-up. However, an additional analysis of exercise change for this subgroup yielded the same non-significant result as for the larger sample. Another reason may be that measurement of exercise behavior in terms of frequency without including a measure of duration/intensity might have prevented accurate classification and underrated possible changes.
There was no differential change from T1 to T2 based on participation in the exercise guidance or the extra health check-up. As described, the one-dimensional measurement of exercise behavior might have prevented detecting change, in particular as the exercise guidance emphasized adequate fitness training and correct use of fitness equipment which might be expected to impact duration or intensity of exercise rather than frequency alone. As for the extra health risk check-up it could be discussed whether the first health profile that was used for baseline assessment of fitness and health parameters and was provided to all might not already have motivated participants into contemplating change, so that the additional monitoring of health status three months later was not able to make a substantial additional contribution. A further aspect to be taken into account is the partial implementation failure. Due to the substantial drop-out, both the exercise guidance and the health-check were implemented as single events and not as a monitoring system providing feedback in regular intervals. Yet another factor could be program failure. A recent review by Vuillemin et al.  on general worksite physical activity interventions reported moderate evidence for effects of longer-term exercise training programs on physical fitness outcomes and exercise behavior but inconclusive or lacking evidence for counseling interventions. Exercise guidance and individual feedback about health and fitness status are both counseling-type components and it might be discussed whether more intense and longer-term guided exercise programs which create socially more binding structures are likewise required in the maritime setting. This might be more difficult to achieve for seafaring than for onshore workplaces, but web-based communication devices might be considered for overcoming logistic problems
Beyond the lack of evidence for effects of the health education modules, it needs to be noted that the change which occurred in fitness might be attributable to the structural changes made by upgrading fitness rooms on board in combination with the treadmill/rowing machine competitions between boats. In a similar vein, a Finnish study on seafarers with high risk factor load installed new fitness rooms on board or improved fitness room equipment, provided exercise guidance and subsidized fitness club visits on shore and found a 25% decrease in inactivity from baseline to the one-year-follow-up .
As for dietary behavior, there was no significant change in reported overeating, while intake of high-sugar products, such as sweets, cake and sodas decreased significantly between T1 and T2. This change was not associated with participating in an additional individual health monitoring, but it might be assumed that the “healthy cooking courses” offered to ship cooks might at least have contributed to this development. As no control group was assigned, no definite effect attribution is possible. However, additional findings from interviews with the participating cooks, which have been reported elsewhere [10, 23] and in Hjarnoe, L. and Leppin, A.: What does it take to get a healthy diet at sea? A maritime study of the challenges of transferring knowledge from a health promotion intervention to the workplace at sea, submittet] suggest that on many ships supply changes were made in terms of reducing fat and sugar content in meals, offering fruit instead of cake and/or abolishing sugared soda drinks.
The Finnish study on health promotion for seafarers similarly introduced training for ship cooks in preparing lighter meals combined with group interventions such as “weight-watcher” groups and individual support from occupational nurses. Seafarers perceived the meals at the one-year-follow up as being healthier than at baseline. Similarly, two recent reviews on general worksite health promotion interventions for employees’ diets found evidence for small to moderate effects of educational and/or structural interventions, particularly for fruit, vegetable and fat intake [22, 29].
Beyond self-report changes in behavior, the most notable was a significant decrease in the percentage of employees with metabolic syndrome. Again, there was no significant association of this change with participating in the extra health risk feedback or in the exercise guidance. Like for the decrease in self-reported intake of high-sugar products, the positive change in the meals served on board due to the cooking intervention for ship cooks might have contributed to this development. In fact, additional sub-analyses (not reported here) showed that the risk factor for metabolic syndrome, which had changed most, was glucose level. This is in contrast to the Finnish study on work site health promotion among seafarers  which also reported improvements in self-reported eating behavior, but did not find changes in related physiological parameters. Both studies were based on pretest-posttest designs though, which clearly restricts internal validity. Also, it is important to note that metabolic syndrome still was highly prevalent in the sample. A US-American cross-sectional study of health characteristics among merchant marine captains and pilots showed similar rates of 39% with metabolic syndrome . In comparison, a Danish study of the general population found only 20% of 20–97 year old males with metabolic syndrome , and a Canadian study from 2011 revealed 18% prevalence among its male participants . In particular, when assuming a healthy-worker effect due to the requirements of frequent health examinations, the rates among seafarers are alarming and indicate an urgent need for intensified intervention efforts.
A major limitation of the study is the possibility of selection bias. 43% of employees did not participate in the first questionnaire round and even more did not take part in the first health profile (58%). Interviews with non-participants of health profile 1 revealed different motives, some of which suggest more random effects, such as misunderstandings about locations or time frames for signing up as well as conflicting sailing schedules. Other explanations, however, indicate more systematic influences, such as seeing lifestyles as a matter of privacy or being afraid that data would be registered and followed by employers, but also feeling no need for personal participation due to an activity status which was already perceived as high. Furthermore, there were sizeable drop-out rates towards T2 of 39% for the questionnaire survey and 40% for the health profile. There did not appear to be substantial differences in the main variables of interest between these two groups at baseline, but it can be expected that a substantial part of the drop-outs were those who did not improve over time so that some of the more favorable developments found might be overestimations. This difficulty to attribute positive changes over time to one or several of the various interventions is furthermore reinforced by reliance on a before-after design without a randomized or in fact any control group. This lack of control group was due to the specific work organization process where crews shifted between ships on a regular basis which made a fixed assignment of crews/ships to an intervention or control condition not feasible. For the health education interventions it was possible to compare participants with non-participants. Such comparisons, however, are naturally problematic due to non-equivalence of the groups, not at least due to differences in motivation to change.
There certainly is a need for more methodologically rigorous studies, but it also needs to be noted that there is a genuine conflict between demands for scientific rigor and stakeholder needs for and interests in workplace interventions . Moreover, the organization of the maritime setting in particular presents practical challenges, which makes control group designs technically hard to achieve due to constantly moving work places and many crew members regularly shifting ships. Lastly, limitations in behavior measurement need to be acknowledged. Like in all studies using self-report measures, reporting bias might have occurred due to social desirability tendencies. Another pertinent problem might be a lack of differentiation in measurement as already discussed for exercise assessment. Similarly, food diaries or more elaborate food questionnaires might have provided more reliable and valid results than single items asking for frequency of consuming different types of food.