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Sexual function of premature ejaculation patients assayed with Chinese Index of Premature Ejaculation

Yi-Ming Yuan1, Zhong-Cheng Xin1, Hui Jiang2, Yan-Jie Guo1, Wu-Jiang Liu1, Long Tian1, Ji-Chuan Zhu2

1Department of Urology, Peking University first Hospital, Beijing 100034, China
2Department of Urology, Peking University second Hospital, Beijing 100034, China

Asian J Androl 2004 Jun; 6121-126


Keywords: premature ejaculation; Chinese index of Premature Ejaculation; latency; sex satisfaction; diagnosis
Abstract

Aim: To assess the psychometric properties of the Chinese Index of Premature Ejaculation (CIPE). Methods: The sexual function of 167 patients with and 114 normal controls without premature ejaculation (PE) were evaluated with CIPE. All subjects were married and had regular sexual activity. The CIPE has 10 questions, focusing on libido, erectile function, ejaculatory latency, sexual satisfaction and difficulty in delaying ejaculation, self-confidence and depression. Each question was responded to on a 5 point Likert-type scale. The individual question score and the total scale score were analyzed between the two groups. Results: There were no significant differences between the age, duration of marriage and educational level (P > 0.05) of patients with and without PE and normal controls. The mean latency of patients with PE and normal controls were 1.61.2 and 10.29.5 minutes, respectively. Significant differences between patients with (26.74.6) PE and normal controls (41.94.0) were observed on the total score of CIPE (P < 0.01). Using binary logistic regression analysis, PE was significantly related to five questions of the original measure. They are the so-called the CIPE-5 and include: ejaculatory latency, sexual satisfaction of patients and sexual partner, difficulty in delaying ejaculation, anxiety and depression. Receiver Operating Characteristic (ROC) curve analysis of CIPE-5 questionnaire indicated that the sensitivity and specificity of CIPE were 97.60 % and 94.74 %, respectively. Employing the total score of CIPE-5, patients with PE could be divided into three groups: mild (>15 point) 19.8 %, moderate (10~14 point) 62.8 % and severe (< 9 point) 16.7 %. Conclusion: The CIPE-5 is a useful method for the evaluation of sexual function of patients with PE and can be used as a clinical endpoint for clinical trials studying the efficacy of pharmacological intervention.

1 Introduction

Premature ejaculation (PE) is a common sexual complaint of men, with a reported prevalence between 30 %- 60 % [1-5]. Despite the high prevalence of PE little research has focused on its assessment technique or treatment method.

The early definitions of PE were mostly based on the ejaculatory latency and/or partner's satisfaction. The current definition of PE is a persistent or recurrent occurrence of ejaculation with minimal sexual stimulation before, on, or shortly after vaginal penetration and before the patient wishes it [6, 7]. The dysfunction is a important source of distress to the man and his partner.

The most widely used assessment guideline in studies on PE was intravaginal ejaculatory latency (IELT) [8-11] and to a lesser extent the number of penile thrusts, while partner information was often included but seldom used as a part of the assessment procedure [12, 13]. It is important to consider that nearly a half of the adult women also suffer from sexual dysfunction [14] and PE patients may also have other sexual disturbances, which further complicate the relationship between the partners. Thus, the definition and methods of clinical evaluation of PE remains a work in progress.

This study was designed to evaluate the psychometric properties and the reliability and specificity of the Chinese Index of Premature Ejaculation (CIPE), a simple and effective approach of evaluating sexual function of PE patients.

2 Materials and methods

 

2.1 Subjects

The subject in this study comprised of 167 PE patients (102 primary and 62 second) and 114 healthy controls. An assistant explained to them the aim of the study and the method to complete the CIPE. Both groups were sexually active, had no difficulty in comprehending CIPE and agreed to complete it based on their sexual activities in the past 6 months (between November 2001 to April 2002). Patients with the following criteria were excluded from the study: 1) not living together with their sexual partner, 2) receiving treatment for PE or erectile dysfunction, 3) taking antidepressant medication within 4 months of the study, 4) drug abusers, 5) heavy smoker and 6) suffering from acute or chronic urinary tract inflammation.

Table 1 lists the basal condition of the subjects. It can be seen that only the ejaculatory latency is significantly different while all other criteria are similar between the two groups.

Table 1. Basal conditions of the subjects. aP > 0.05, cP < 0.01, compared with controls.

 

Age (Year)

Married years

Education (year)

Ejaculatory latency (min)

Patients (n=167)

34.710.1 (21~74)

8.39.2 (1~50)

8.2 ?3.5

1.61.2 (0.5~4.0)c

Controls (n=114)

 33.89.4 (24~70)a

 7.39.1 (1~40)a

9.3 ?4.8a

 10.29.5 (2~35)

2.2 CIPE

The CIPE (Table 2) was drafted in terms of the sexual activity of PE patients. The questions of the CIPE include: sexual libido (Q1), frequencies of erection hard enough for sexual intercourse (Q2), frequencies of maintaining erection to complete sexual intercourse (Q3), IELT (Q4), difficulty in prolonging sexual intercourse (Q5), sexual satisfaction (Q6), partner's sexual satisfaction (Q7), frequency of partner reaching orgasm in sexual intercourse (Q8), confidence in completing sexual activity (Q9), frequency of feeling anxious, depressed or stressed in your sexual activity (Q10). Each questionnaire was responded to on a 5 point Likert-type scale.

Table 2. Chinese Index of Sexual Function for Premature Ejaculation (CIPE).

Q1. Your sexual libido or interest?
1. Very low
2. Low
3. General
4. High
5. Very high

Q6. Your sexual satisfaction?
1. Very dissatisfied
2. Always dissatisfied
3. Generally satisfied
4. Often satisfied
5. Always satisfied 

Q2. Do you have erections hard enough for sexual intercourse?
1. Almost never
2. Seldom
3. Half of time
4. Often
5. Always

Q7. Your partners sexual satisfaction?
1. Very dissatisfied
2. Always dissatisfied
3. Generally satisfied
4. Often satisfied
5. Always satisfied 

Q3. Can you maintain erection to complete sexual intercourse?
1. Almost never
2. Seldom
3. Half of time
4. Often
5. Always

Q8. Does your partner reach orgasm in sexual intercourse?
1. Almost never
2. Seldom
3. Half of time
4. Often
5. Always

Q4. How long from intromission to ejaculation?
1. Too short (<30 sec)
 6.  >4-5 min (min)
2. Very short (<1 min)
 7.  6-10 min (min)
3. Short (<2 min)         8. 11-20 min (min)
4. Often short (<3 min) 9. 21-30 min (min)
5. Not short (>3 min)   10. 30-45 min (min)    

Q9. How about your confidence in completing sexual activity?
1. Very low
2. Low
3. General
4. High
5. Very high

Q5. Can you prolong the intercourse time?
1. Very difficult
2. Always difficult
3. Difficult
4. Seldom difficult
5. Not difficult      

Q10. Do you feel anxiety, depression or stress in sexual activity
1. Always
2. Often
3. Half of time
4. Seldom
5. Almost never

Each of the questions was designed to be answered by the subject on a 5 point Likert-type scale, generating individual item scores as well as a total score. If the IELT of the patient was more than 3 minutes, the score of Q4 was 5 point.

2.3 Statistical analysis

The data for statistical analysis included age, duration of marriage and education level, individual responses to 10 CIPE questions and the total score of the CIPE questionnaire. Independent-samples t test and nonparametric tests were used to analyze the difference between the 2 groups. To examine the specific domains of the 10 CIPE questions, binary logistic regression analysis was performed. For analysis of sensitivity and specificity for the total CIPE score, the delimitation score of the integral was fixed according to the Receiver Operating Characteristic (ROC) analysis. If the integral score of Q2 and Q4 was less than 8 points, the patient was considered as combined with ED.

3 Results

3.1 Comparison of CIPE between groups

The total scores of CIPE-10 questionnaire in PE patients and normal controls were 26.74.6 (14~36) and 41.94.0 (34~50), respectively (P < 0.01). It can be seen from Figure 1 and Figure 2 that the scores were significantly different between the two groups in all the 10 questions (P < 0.01).

Figure 1. The mean scores of each of questionnaires domain assessed by CIPE in PE patients and normal controls (NC) showing significant differences. Data presented as meanSD.

Figure 2. The distribution of the frequencies of each score in questionnaire domain assessed by CIPE in PE patients and normal controls (NC) showing significant difference. bP<0.05, cP<0.01, compared with normal control.

3.2 Binary logistic regression

Binary logistic regression analysis showed that Q4, Q5, Q6, Q7 and Q10 were closely related to PE (Figure 3) and the following formula was obtained. When they were entered into the formula, PE can be correctly diagnosed (P < 0.01), the sensitivity and specificity being 100 %.

P= E -534.164+28.130 XQ4+80.443 XQ7+27.599 XQ5+53.636 XQ6-26.273 XQ10/( 1+ e -534.164+28.130 XQ4+80.443 XQ7+27.599 XQ5+53.636 XQ6-26.273 XQ10 )

With this approach, the CIPE integral scores of the PE patients are 12.12.7 (5~18) and those for the normal controls, 21.42.1(16~25), the difference being highly significant (P < 0.01) (Figure 3).

Figure 3. The scores of each domain of CIPE-5 (Q4, Q5, Q6, Q7, Q10) in PE patients and normal controls (NC) showing significant differences. cP < 0.01, compared with normal control.

3.3 ROC analysis

The result of ROC analysis according to CIPE-10 showed that the area under the ROC curve was 1.000.02 (confidence interval 0.99~1.00, P < 0.01) and the area under the ROC curve according to CIPE-5 was 1.000.02 (confidence interval 0.99~1.00, P < 0.01). If the delimitation score of the CIPE-10 integral score was 35, the sensitivity was 97.60 % and the specificity was 94.74 %, while the positive predictive value was 96.43 % and the negative predictive value was 95.58 % (c2=236.34, P < 0.01). If the delimitation score of the CIPE-5 integral score was 18, the sensitivity was 97.60 % and the specificity was 94.74 % while the positive predictive value was 96.45 % and the negative predictive value was 96.43 % (c2=240.14, P < 0.01). According to the above result, 35 scores in CIPE-10 or 18 scores in CIPE-5 may be considered the delimitation point to distinguish PE from normal controls.

3.4 Classification of PE

Based on the CIPE-5 total scores, the PE patients could be further subdivided into three severity groups as follows: mild (>15 point) 19.8 %; moderate (10 - 14 point) 62.8 % and severe (< 9 point) 16.7 % of the patients. In this study, 102 (61.1 %) cases were primary PE and 85 (38.9 %), secondary PE; 102 (62.9 %) cases were pure PE and 62 (36.1 %), PE with ED. ED may be considered when the integral scores of Q2 and Q3 were less than 8 point.

4 Discussion

There were significant differences in the individual and the total score on the 10 CIPE questions between the PE subjects and normal controls. The 10 questions could be reduced to 5 in accordance with the result of the binary logistic regression. These 5 questions are: ejaculatory latency (Q4), difficulty in delaying ejaculation (Q5), sexual satisfaction of patient (Q6), sexual satisfaction of partner (Q7) and feelings of anxiety or depression in sexual activity (Q10). Employing a cutoff score of 18, the sensitivity of CIPE-5 was 97.60 %, the specificity 94.74 %, the positive predictive value was 96.45 % and the negative predictive value was 96.43 %. The CIPE-5 allowed a further sub-classification of PE patients into three groups. The other questionnaires include Q1, Q2, Q3, Q8 and Q9 also showed significant difference between PE and normal control, but they are less significantly related to PE than that of CIPE-5.

CIPE-5 can be a useful approach for the evaluation of patients with PE and can also be used as a clinical endpoint to assess the efficacy of pharmacological intervention.

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Correspondence to: Dr. Zhong-Cheng Xin, Department of Urology, 1st Hospital, Peking University, Beijing 100034, China.
Tel: +86-10-6617 1122 ext 2843, Fax: + 86-10-6612 9625
Email: xinzc@bjmu.edu.cn
Received 2003-06-24 Accepted 2004-04-22