The Relationship of Pre-Operative Stress Level to Sustained Outcome in Gastric Bypass Surgery

Purpose: Previous research has shown that pre-operative health status can serve as a moderator in enhancing the accuracy of certain variables for predicting sustained weight loss after gastric bypass surgery. The present study investigated the role of pre-operative stress level as a moderator in identifying useful pre-operative predictors of sustained weight loss.

Materials and Methods: Follow-up data at a mean of 3.2 years post-operatively were available for 111 patients who had undergone pre-operative assessment on 227 variables including four psychological assessment instruments. These measures were studied for their success in predicting sustained weight loss separately for patients who were under low and high pre-operative stress.

Results: As anticipated, several types of variables (support, coping skills, good adjustment, and good cognitive functioning) predicted success for both groups. In addition, for low-stress patients, social drinking and self-efficacy variables (strong expectations of a broad range of positive changes), and a broader range of personal support variables were the best predictors. For high-stress patients, the best predictors included the presence of a troubled intimate relationship, lack of attention to personal health matters, an active history of smoking, and the possible need for psychiatric medication. Overall, the results show some consistency with the basic postulates of self-determination theory.

Conclusion: The findings provide further support for the view that the investigation of pre-intervention variables can provide useful information in enhancing the predictive accuracy of the success of major life interventions in medical and other settings.
 

Gastric bypass surgery; Weight loss; Pre-operative health
 

It has been stated that the area of greatest concern in gastric bypass surgery (GBS) is not the achievement of an initial weight loss, but sustaining this loss and continuing to lose weight over time [1]. This statement is consistent with the authors’ own work, in which, after a mean weight loss of 45.61 kg (16.42 BMI) after the first post-operative year (0-1 year), the mean change over the subsequent two years (1-3 year) was essentially zero (0.28 kg; 0.15 BMI) [2]. The authors also found that the best pre-operative predictors of the 1-3 year weight loss were mostly different from the predictors of the 0-1 year weight loss as reported by Lanyon and Maxwell [3].

Because the major predictor of the 0-1 year change but not a predictor of the 1-3 year change was good pre-operative health, it was hypothesized that the predictors of 1-3 year change for patients in good physical health prior to surgery would be different from those whose pre-operative health was poor. These hypotheses were borne out [4].

However, more relevant for practical utility would be pre-operative predictors of weight loss over the entire period (0-3 years). These predictors were also different for good and poor pre-operative health patients, and tended to mirror the 1-3 year loss comparisons. For good pre-operative health patients, they centered around variables related to psychological distress and poor self-concept, but strong coping skills and strong expectations of major life improvements as a result of the surgery. For poor pre-operative health patients, the predictors of success were quite different. They involved strong personal support, life satisfaction, and good psychological adjustment and happiness, but little health-related knowledge. Overall, they characterized persons who had strong dependency needs that were being fully met by others. A possible explanation for these findings is that extreme support and good psychological adjustment are necessary in order for persons burdened by poor health to successfully take on this additional life task.

These findings show that pre-operative health serves as a moderator for number of predictors of sustained success in GBS, thus providing a means of improving the accuracy of predicting outcome, and assisting in the decision as to whether to utilize GBS as an approach to obesity for any particular patient. The findings raise the possibility that other pre-operative characteristics could also be found to serve a similar function, thereby improving predictive accuracy even further.
 

Another pre-operative variable that could logically be considered to impact GBS patients in their efforts at continued weight loss is stress level. It can be readily seen that in addition to impairments and incapacities due to medical difficulties, there can also be impairments and incapacities due to stresses that are not medical in nature. Such stresses could be logically expected to interfere with the sustained efforts that are needed to maintain weight loss after GBS. Nevertheless, many patients with high pre-operative stress do continue to lose weight. It was therefore hypothesized that, as with the pre-operative health variable, the pre-operative predictors of sustained outcome (0-3 year) would differ between persons with low pre-operative stress and those with high pre-operative stress. Thus, as with pre-operative health level, it was hypothesized that pre-operative life stress level would serve as a moderator in predictor-outcome relationships.
 

Participants

Assessment of pre-operative stress

Comparison of low and high pre-operative stress patients

The general hypothesis of the present study was that pre-operative predictors of sustained success (over three years) for GBS patients would differ according to pre-operative stress level. This hypothesis followed from the previous findings of major differences in outcome predictors between patients with good and poor pre-operative medical health status.

The present results showed several predictors of success in common for both low-stress and high-stress patients: good support from family and friends, good personal coping skills, and good psychological and cognitive functioning.

However, the groups differed as follows. The major characteristic of the successful low-stress patients was their strong and broad expectations for major life improvements-spanning work-related, social, physical, and general confidence and life-satisfaction areas. In addition, these patients had been in their major relationship for only a relatively brief period of time, and the overall number and range of personal support variables was even stronger than for high-stress patients. For the high-stress patients, the strongest predictor was the presence of a troubled relationship including separation, a lack of interest and/or knowledge regarding health matters (in general and also regarding their own health status), and some possible adjustment difficulties during adolescence.

It is instructive to compare these results with those of the previous study, in which the outcome predictors for good pre-operative health and poor pre-operative health patients were studied. Similar to present study, the strongest predictors for the good-health patients involved strong and broad expectations for massive life improvements. But interestingly, these patients had relatively poorer psychological adjustment and poor self-concept. And analogous to the present findings, a strong predictor for the poor pre-operative health patients was poor knowledge and little interest in matters involving health information in general and also in their own health. But the poor-health patients who improved the most had massive personal support and were happy and well-adjusted-essentially, they were happy people who were being were fully and completely taken care of.

In viewing the present results, it is logical to view high pre-operative stress as potentially interfering with progress (continued weight loss), noting that the low-stress patients did not have such interference. The task confronting the low-stress patients was a more straightforward one. It is no surprise that success for both groups was related to the variables that predict success in any therapeutic endeavor: good coping skills, good personal support, and good personal adjustment. But a major predictor for low-stress patients was a strong expectation of success across many life areas. This characteristic, termed self-efficacy by Bandura [9], has been repeatedly shown to be a strong predictor of successful therapeutic change.

What of the patients with high pre-operative stress? The results suggest that many of them had serious relationship problems-perhaps the cause of the high stress; and it can be speculated that a desire for a better relationship might have been a driving force for successful sustained weight loss. Their lack of interest in health matters suggests that their approach to change was idiosyncratic or autonomous, rather than following specific instructions on what they were “supposed” to do.

The pattern of findings in both the present and the previous study show some degree of correspondence with predictions that could be made from self-determination theory as applied to health contexts [10]. A basic tenet of this theory is that “behavior change is more effective and lasting when patients are autonomously motivated” (p. 325). Also included is the importance of three basic psychological needs to “motivate the initiation and long-term maintenance of health behaviors” (p. 326): autonomy, competence, and relatedness. Such themes can be seen in the variables related to success in the present authors’ work. It is particularly noted that for patients with extra burdens (poor health; high stress), the successful patients were those who ignored the “rules”-the conventional health-related knowledge-and simply did it their own autonomous way. And for the good-health and low-stress patients, the motivation for successful change appears to have been intrinsic-the personal drive to have a better life, rather than based on external factors.

A word should be said about two unexpected variables that were found to be related to success in the present study: significant alcohol use for low-stress patients, and habitual tobacco use for high-stress patients. As a possible explanation, it is noted that Table 2 shows many interpersonally relevant predictors for the low-stress improvers, compared with relatively few for the high-stress improvers (Table 3). Given than alcohol and tobacco are, broadly speaking, utilized as stress reducers, it is consistent that the high-stress patients utilized the more socially related behavior (alcohol), versus a non-personal stress reducer (smoking) by the high-stress improvers. It is noted that “social drinking only” was shown to be a specific predictor of success for the former group.

Several limitations of the present study should be recognized. First, in regard to the follow-up data, it is noted that the procedures for obtaining participants’ weight after three years were somewhat rudimentary. This would have had the potential effect of reducing the reliability of these data. In future work, it might be preferable to obtain this information in the context of individual in-person interviews. A second issue involves the considerable variability in the extent to which patients participated in post-operative support groups and individual counseling. The effects of this activity on ultimate outcome remain unknown. Third, it is recognized that the study utilized a large number of predictors, yielding a comparatively small number of significant correlations (although greater than would have been expected by chance alone). While none of these limitations are likely to have biased the basic findings of the study, they should be taken in to consideration in future research of this nature.

The results of the present study add to previous findings that useful moderators can be found for enhancing pre-operative prediction of outcome in GBS. It would be of interest to investigate these variables (health status, life-stress) and possibly others (e.g., general psychological adjustment) for their possible relevance in improving outcome predictions in other significant life interventions, whether surgical or of another type.
 

Richard I. Lanyon: Receives royalties from the sale of the Multidimensional heath Profile; Barbara M. Maxwell: No conflict of interest.
 

Informed consent was obtained from all individual participants included in the study.
 

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.