Prevalence of insomnia in various psychiatric diagnostic categories
Abstract
Abstract Sixty percent of 536 new referrals to a psychiatric clinic at a general hospital complained of insomnia. Prevalence was high in all psychiatric categories, especially in physiologic disorders, somatoform disorders and mood disorders, followed by epilepsy. Complaints of difficulty in falling asleep were high in the physiologic and somatoform disorder groups. Complaints of nocturnal awakening were high in the anxiety and physiologic disorder groups, while complaints of early morning awakening were high in the organic and mood disorder groups. Prescription rates of hypnotics was most prevalent in the mood and adjustment disorder groups, whereas a non-pharmacological approach, including psychological education and behavioral therapy, was applied mainly to the physiologic disorder group.
INTRODUCTION
There have been several studies on the prevalence of insomnia among new referrals to general hospitals1 and on the prescription rates of hypnotics among patients at general hospitals.2,3 These studies have indicated a high prevalence of insomnia and a high usage rate of hypnotics among psychiatric patients. However, the prevalence of insomnia and the types of insomnia, as well as the usage rates of hypnotics among different psychiatric categories have not yet been clarified. The present study aims to clarify these points among first-visit patients to a psychiatric clinic at a general hospital and to evaluate the treatment plan for insomnia in different psychiatric categories.
SUBJECTS AND METHOD
All new patients attending the Department of Neuropsychiatry, Surugadai Nihon University Hospital from April 2000 to March 2001 participated in the study. Five hundred and thirty-six patients (260 males and 276 females) consented to completing a questionnaire, which included questions about the presence and various types of insomnia. After clinical investigations, the doctors in charge diagnosed each patient’s psychiatric category according to the ICD-10 classification. Thereafter, a treatment plan for insomnia, including either a prescription for hypnotics or a non-pharmacological approach, among the different psychiatric categories was evaluated. Using χ2 test, the prevalence and prescription rates for each psychiatric category were compared statistically with those for new patients with epilepsy.
RESULTS
The prevalence of insomnia in many psychiatric disorder groups (ICD-10 categories: F0, F3, F41, F43, F45, and F5) was higher than that in epilepsy (G4), especially in the physiologic disorder (F5), somatoform disorder (F45), and mood disorder (F3) groups (Table 1). In decreasing order, the prevalence of difficulty in falling asleep was high in categories F5, F45, and the adjustment disorder (F43). That of nocturnal awakening was high in the anxiety disorder (F41), and in categories F5 and F43. That of early morning awakening was high in the organic disorder (F0), and in categories F3 and F43. The prescription rate of hypnotics was also higher in many psychiatric disorders (ICD-10 categories: F2, F3, F41, F43, F45, and F5) in comparison to epilepsy, especially categories F3, F43, and F41. Short-acting hypnotics were prescribed most frequently in all categories except for epilepsy, which was treated with medium- or long-acting hypnotics. The prescription rate of hypnotics was relatively low and the non-pharmacological approach, including psychological education and behavioral therapy, was applied to the physiologic disorder group.
| ICD-10 code | No. cases | Percent of insomnia(Difficulty in falling asleep, midnightawakening, early morning awakening) | Percent of prescribed hypnotics(Short-acting, medium-acting,long-acting) |
|---|---|---|---|
| F0 Organic mental disorders | 27 | 67* (19, 37, 30) | 11 (4, 7, 0) |
| F2 Schizophrenic spectrum | 26 | 50 (30, 12, 31) | 19* (15, 3, 0) |
| F3 Mood disorder spectrum | 68 | 69* (43, 29, 38) | 43* (24, 16, 3) |
| F41 Anxiety disorders | 70 | 63* (36, 13, 44) | 31* (21, 10, 0) |
| F43 Adjustment disorder | 116 | 65* (45, 39, 20) | 35* (23, 10, 2) |
| F44 Dissociative disorder | 24 | 54 (42, 21, 8) | 13 (13, 0, 0) |
| F45 Somatoform disorder | 45 | 71* (49, 29, 18) | 22* (16, 7, 0) |
| F5 Physiologic disorders | 32 | 78* (63, 41, 16) | 28* (16, 9, 3) |
| G4 Epilepsy | 66 | 26 (20, 11, 5) | 3 (0, 2, 2) |
- * P < 0.01 (significantly higher than epilepsy group, χ 2 test).
DISCUSSION
Ishigooka et al. have reported that 11.7% of new referrals to general hospitals had insomnia, among whom those who were referred to the psychiatric department had the highest prevalence of insomnia; 17.5% in male patients and 15.4% in female patients.1 Conversely, the prescription rate of hypnotics in psychiatric outpatients have been reported to be almost twofold compared with that of other department outpatients at general hospitals.2,3 Compared with these results, the present study showed a markedly high prevalence of insomnia (60%) among psychiatric new referrals, whereby one should consider that in cases of new psychiatric patients, insomnia may be an early sign of psychiatric problems or symptomatic of psychiatric disorders. For symptomatic insomnia, psychotropic drugs other than hypnotics were preferred, and for sleep problems per se, hypnotics were prescribed. A high prevalence of insomnia, especially that of difficulty in falling asleep, was seen in cases with a physiological disorder, but the prescription rate of hypnotics was relatively low for this group. This is because most patients in this category have a fear of insomnia and for using hypnotics, thereby non- pharmacological interventions such as psychological education and behavior therapy are preferred.
