Introduction

 

Lower urinary tract symptoms due to Benign Prostatic Hyperplasia (BPH) are common with an age specific prevalence of 50-85% in men aged more than 50 years old. The measurement committee of the American Urological Association (AUA) designed a symptom index (AUA-7) for BPH.1,2 In Iranian population, BPH is also common and its prevalence increases with age, from 1.2% in men aged between 40-49 to 36% in men aged >70 years.3 The AUA-7 was recommended by the World Health Organization-sponsored International BPH Consultation, as the official worldwide symptoms assessment tool for patients with BPH. Together with an extra component on quality of life (QoL), the AUA-7 was then named the International Prostate Symptom Score (IPSS), which was in turn recommended by the World Health Organization-sponsored International Consultation on BPH as the instrument of choice in the quantification of BPH-related urinary symptoms in clinical trials of treatment modalities for symptomatic BPH.4-6 Revalidations of translated questionnaires along with retesting of reliability are parts of the process for ensuring that data can be reliably compared and aggregated.7,8 We performed the current study to assess the reliability and validity of the Persian version of the IPSS in the Iranian population.

 

Methods and Materials

 

Validity and reliability of the Persian version of IPSS were assessed through two different methods. First the original questionnaire (English version) was translated into Persian (Farsi) language by our licensed translation group. Following a 3-week delay, the Persian version was translated back into English by another licensed translation group. Then two English questionnaires were compared and no significant difference was seen between them. Consequently, validity of Persian version of IPSS was confirmed. Reliability of the translated questionnaire was studied in a group of patients with BPH. Diagnosis of BPH was confirmed by one urologist in all cases, and was principally based on clinical criteria, including medical history and physical and digital rectal examinations. Patients who had any of the following were excluded from the study: prostate cancer, diabetes mellitus, medical history or physical examination suggesting a neurologic disorder, current prostatitis, cystitis, urinary infection, urethral strictures, kidney stones, psychiatric disorders, previous pelvic trauma or surgery, previous surgical procedures for BPH, permanent bladder catheter, or use of drugs affecting bladder function. First, the patients were interviewed regarding the Persian questionnaire; 3 weeks later they were interviewed again by using the same questionnaires. Total scores and score of each question were recorded. Sample size was calculated with a level of significance of 0.05 and power of 80%, according to which 50 patients were estimated to be required for the study. Internal consistency of the Persian version of IPSS was assessed by calculating Cronbach’s α test. Reliability was assessed by using Student T-test and Paired T test. All statistical analyses were performed using the SPSS-13 software. A P value <0.05 was considered as statistically significant.

 

Results

 

A total of 50 patients participated in this study. Mean Age ± SD of patients was 61.5 ± 8.3 years. Internal consistency for the Persian version of IPSS was 0.7 with use of Cronbach’s α test. With regard to stratification of total scores of the 50 patients, 22% (11 patients) had mild symptoms (0 <Total score ≤ 7), 61% (30 patients) had moderate symptoms (7<total score ≤20) and 17% (9 patients) had severe symptoms (20<total score ≤35). Table-1 shows mean total score and each question score in the first interview and 3 weeks later. Test-retest reliability that was assessed using these data, showed no significant difference between the scores before and after 3 weeks (P value=0.9).

 

Discussion

 

This Persian version of the IPSS has proved to be valid and reliable among Iranian patients with BPH. Measurement properties of the Persian version of IPSS validated among Iranian population were compared with the measurement properties of the original IPSS validated in the United States. The results showed that measurement performance properties of the Persian version approached that of the English version. Matched with the present study, an article in the same setting assessed validation and reliability of Spanish version of IPSS. It showed results with an internal consistency of 0.79.9,10 Also, test-retest reliability of that study was assessed in 57 patients and showed that IPSS had an Intra class correlation coefficient (ICC) of 0.87 (P value=0.01) and a Pearson’s product moment coefficient of 0.92 (P-value=0.01). Therefore the Spanish version of IPSS was approved valid and reliable.11 In another study on Malaysian population, a total of 50 respondents were enrolled in the validity and reliability study. Internal consistency of the Malaysian version of IPSS indicated a high level of homogeneity among scale items. Test-retest reliability assessed in those patients after 12 weeks, demonstrated a Malaysian version of IPSS intra class correlation coefficient (ICC) of 0.70 (P-value=0.001). Therefore, the validity and reliability of Malaysian version of IPSS was approved.12 In another study the Arabic version of IPSS was proved to be valid and reliable for patients with BPH.13 Results of their research are comparable with our confirmatory findings for validity and reliability of the Persian version of IPSS. It is important to mention that the IPSS is proven to be a cost effective, sensitive, and specific screening tool for diagnosing and controlling the prostate cancer.14

 

 

Conclusion

 

Our results confirmed that the IPSS is a favorable, psychometrically robust, symptoms-based instrument that has proved to be suitable for implication in Iranian population.

 

Limitations

 

We did not measure sensitivity to changes for this Persian version of IPSS; but in other articles this indicator was measured by use of IPSS before and after a procedure for BPH such as TURP.1,2