Should the Population be Offered General Health Screenings?

Even though the Cochrane review to which Olivarius refers contains few randomized examinations of “health promotion” for persons with a low risk of cardiovascular disease, we agree that interventions for these groups are not as effective as in groups at higher risk. Nevertheless, finding persons to whom a more cost-effective intervention can be offered is necessary. This imperative is mentioned in our report. Regarding Olivarius’ 4 comments:

1. It is an illusion to think that an imbalance between treatment groups can be rejected by comparing different factors between them. There is always a risk for imbalance that may lead to confounding, if not on known factors then on unknown factors. The randomized experimental design used in the Ebeltoft project is the strongest instrument to avoid such an imbalance. But it is a mistake to believe that the groups become identical by a randomization procedure.⁵ Most reviewers and readers do, however, feel more comfortable if no imbalance is apparent for the most basic factors such as sex, age, etc. The report thus presented a few such factors and no imbalance was found between the groups.
2. It is a well-known fact that unhealthy and vulnerable persons are more likely to drop out from a study than are healthy individuals. It is therefore not possible to carry out a follow-up study and avoid the described dropout problem. This pitfall is one of the reasons why evaluating results from nonrandomized studies is difficult. In our study the groups were compared in accordance to the intentto-treat rule to adjust partly for this problem, but dropout can never be totally avoided in a clinical setting. In a randomized study the biggest problem arises if the dropout is differentiated, meaning if the more unhealthy individuals drop out from one group but not from other groups. In the Ebeltoft project the attendance rate between the control group and the intervention group was not different after 5 years regarding sex, age, baseline smokers, and baseline body mass index.
3. We used a cardiovascular risk score developed by Anggard and associates⁶ based on sex, familial inheritage, tobacco use, blood pressure, serum cholesterol (total) concentration, and body mass index, which also figures in other cardiovascular risk scores and which are commonly accepted factors in the estimation of future risk of heart diseases. As any score is difficult to evaluate, we also presented the relevant clinical outcome measures. The mean value of the cardiovascular risk score is 5.50 (SD 3.18) in the control group and 4.98 (SD 2.80) in the intervention group (P<.01) if sex and inheritage are omitted; if smoking is also left out the scores are 4.33 (2.60) and 3.91 (2.34), respectively (P<.01).
4. Our study shows that a health screening is suitable to reduce the population’s cardiovascular risk profile, with or without a planned discussion with the general practitioner. All baseline participants who were offered a health screening and who were warned of an elevated risk of coronary heart disease were, for ethical reasons, encouraged to see their general practitioner even if they belonged to the group that was not automatically offered a health discussion.

Although these consultations probably were not as extensive and detailed as those offered as part of the study, they may confound the difference in the degree of intervention. But it cannot be concluded that discussions with the general practitioner have no effect. The possibility of having a health discussion must exist, but planned health discussions do not add further to the effect. Likewise, the control group participants may have changed their behavior and consulted their general practitioner more often than they had previously. Such behavioral changes and other conditions mentioned in the report indicate that the detected effect is an underestimation of the real effect.

The goal of our study was to focus on the general effect of the intervention. We found that health screenings can improve the cardiovascular risk profile in the general population. We did not consider whether health screenings "should be" offered to the general population, an arena that delves into organizational, political, and economic questions.

Marianne Engberg, MD, PhD, Bo Christensen, MD, PhD, Bo Karlsmose, MD, PhD, Jørgen Lous, MD, DMSc, and Torsten Lauritzen, MD, DMSc, Aarhus Universitet, Denmark. E-mail: me@alm.au.dk