Correspondence

Cost as a Barrier to Medical Care

N Engl J Med 1999; 340:1293April 22, 1999

Article

To the Editor:

In “Cost as a Barrier to Medical Care in Relation to Unemployment Rates” (Nov. 26 issue),1 it seems to me that Figure 1 is misleading. The y axes for the two plotted variables have different points of origin, but more important, different scales. The patterns of monthly unemployment rates and the prevalence of the perception that cost was a barrier to medical care cannot be compared validly on such a misleading graph. Plotted correctly, the two lines would not overlap or parallel each other as they appear to.

Maxim Lewkowski
McGill University, Montreal, QC H3G 1L2, Canada

1 References

1. 1

   Nelson DE, Thompson BL, Bland SD. Cost as a barrier to medical care in relation to unemployment rates. N Engl J Med 1998;339:1644-1645
   Full Text | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: We appreciate Lewkowski's comments. Had we plotted our data using the same points of origin or the same scales, the two lines would not have overlapped. We disagree, however, that this is misleading.

Different points of origin were used on the y axes to make it easier to visualize our data, since estimates of the prevalence that cost was perceived as a barrier to medical care were about twice as high as unemployment rates. This approach is analogous to comparing cancer-incidence trends according to age by graphing data on different scales.1 When our data are displayed with the same scale width for both y axes (not shown), the similarity of the two trend lines remains comparable.

David E. Nelson, M.D., M.P.H.
Betsy L. Thompson, M.D., M.S.P.H.
Shayne D. Bland, M.S.
Centers for Disease Control and Prevention, Atlanta, GA 30341-3717

1 References

1. 1

   Harras A, ed. Cancer: rates and risks. Bethesda, Md.: National Institutes of Health, 1996. (NIH publication no. 96-691.)