The essential feature in hypochondriasis is preoccupation not with symptoms themselves but rather with the fear or idea of having a serious disease, based on the misinterpretation of bodily signs and sensations (see Table 13–1). The preoccupation persists despite evidence to the contrary and reassurance from physicians. Some degree of preoccupation with disease is apparently quite common. As reviewed by Kellner (1987), 10%–20% of "normal" and 45% of "neurotic" persons have intermittent, unfounded worries about illness, with 9% of patients doubting reassurances given by physicians. In another review, Kellner (1985) estimated that 50% of all patients attending physicians' offices "suffer either from primary hypochondriacal syndromes or have 'minor somatic disorders with hypochondriacal overlay'" (p. 822). How these estimates relate to hypochondriasis as a disorder is difficult to assess because they do not appear to distinguish between preoccupation with symptoms (as is present in somatization disorder) and preoccupation with the implications of the symptoms (as is the case in hypochondriasis).