Hypothesis / aims of study
The International Prostate Symptom Score (IPSS) is a worldwide frequently used questionnaire by clinicians and researchers, to measure severity of LUTS and the perceived loss of quality of life. The IPSS is mentioned in guidelines on urinary incontinence (e.g. the Dutch Physiotherapy guideline, the American Physiotherapy Association and the European guideline of European Association of Urology). IPSS is a free available 8-item self-report questionnaire and takes 5 minutes to fill in. The IPSS identifies and quantifies the severity of incomplete bladder emptying, frequency of urination, intermittency, urgency, weak urine stream, straining and nocturia over the past month. Although initially developed for LUTS in men, the questionnaire is also used in women.
Aim is to demonstrate the reliability, validity and responsiveness of all translated versions of the IPSS in men and women. Methodological quality of published studies are taken into account to reach an advice:" Can the use of the IPSS in primary care be advocated?"
Study design, materials and methods
A narrative review is carried out in 3 databases with the following search string:
Search: (((((IPSS[Title] OR "International Prostate Symptom Score"[Title]) AND ("Reproducibility of Results"[Mesh] OR reliab*[tiab] OR validity[tiab] OR reproduc*[tiab] OR responsive*[tiab] OR (feasibility[tiab] NOT "Feasibility Studies"[Mesh]) OR internal consistenc*[tiab] OR "Observer Variation"[Mesh] OR observer variation*[tiab] OR intraobserver variation*[tiab] OR interobserver variation*[tiab] OR observer variabilit*[tiab] OR interobserver variabilit*[tiab] OR intraobserver variabilit*[tiab] OR measurement error*[tiab] OR interpretability[tiab] OR "Sensitivity and Specificity"[Mesh] OR accura*[tiab] OR "limit of detection"[tiab] OR "detection limit" [tiab] OR "detection limits"[tiab] OR "roc curve"[tiab] OR "roc curves"[tiab] OR "roc analysis"[tiab] OR "roc analyses"[tiab] OR "receiver operating characteristic"[tiab] OR "receiver operating characteristics"[tiab] OR sensitivity[tiab] OR specificity[tiab] OR prognos*[tiab] OR properties[tiab] OR responsive*[tiab]))) AND (prostate[tiab])))
The Cosmin screening list was used to score for methodological quality.
Results
The COSMIN scores were fair for hypothesis testing and ranged from fair to good for criterion validity.
Combined with the inconsistency of findings, number of studies (n = 5), total sample size (n = 788) and COSMIN scores, the level of evidence in the systematic review was graded as moderate for the validity of detection of BOO using questionnaires.
Psychometric properties of the IPSS vary, depending on the language used. Overall, the IPSS has been found a reasonable to good internal consistency (Cronbach’s alpha= 0,70-0,83). The test-retest reliability is high (intraclass correlation coefficient (ICC) = 0,80-0,95), additionally, the ICC for question 8, the Quality of Life question was even higher ( 0,91-0,99).
Criterion and construct validity properties of the IPSS are not sufficient in men with bladder outlet obstruction (BOO) and benign prostate obstruction (BPO). Poor correlations are demonstrated between IPSS scores and maximum flow rate, postvoid residue and obstruction grade numbers (r=-0.07 to 0.06). Different IPSS item-score cut-off values to indicate obstruction (maximum flow rate <10, <15, <19 mL/s) demonstrated poor to moderate sensitivity (25% to 74%) and moderate to good specificity (55% to 86%) compared to uroflowmetry.. A lower flow rate cut-off point resulted in a lower sensitivity and higher specificity.
The IPSS yielded poor correlations with uroflowmetry recordings, detrusor pressure at maximum flow (r =0.18) and obstruction grade numbers (r=0.15 to 0.16). The COSMIN scores were fair for hypothesis testing and ranged from fair to good for criterion validity.
Interpretation of results
Weaknesses and strengths can be reported on the psychometric quality of the IPSS. Strength is that the IPSS is designed to be an easy, short, free available self to administer questionnaire. However, some studies show that a successful completion of the IPSS is more difficult in low educated patients. Therefore, some patients need assistance to complete the questionnaire and understand the content of the questions or need alternatives such as the visual prostate symptom score. In the English language, the psychometric quality is sufficient. The internal consistency is sufficient to good in all languages.
Weaknesses are that a) not in all languages the psychometric quality is thoroughly tested, b) consistent evidence on responsiveness is lacking and c) question 8 is meager to test Quality of Life, properly.