Frequency volume charts: an indispensable part of lower urinary tract assessment

Frequency volume charts (FV charts) are widely used by those interested in lower urinary tract function. However, there has been little systematic work on the value and design of FV charts as they have evolved over the years as clinical tools rather than as research instruments. Although FV chart design has developed over the last 20 years, there is no standard and charts vary from simple frequency charts up to urinary diaries which record not only frequency, volume, urge episodes, pad usage and fluid intake, but also the patients' activities in relation to their lower urinary tract symptoms. Studies have shown that charts can be relatively complex and still be acceptable to patients, providing proper instruction is given, either by written advice or at face to face interviews. The correlations between the answers to simple questions concerning frequency and nocturia and the data extracted from FV charts are variably strong: nocturia, pad usage and incontinence episodes correlate well, whereas urinary frequency correlates less closely. A number of conclusions on frequency volume charts can be made. The chart is best kept for 7 days in order to cover both work and leisure periods. The daytime should be separated from the night-time, and this is particularly important in assessing older patients with possible nocturnal polyuria. Addition of voided volume measurement to the frequency chart allows the construction of a simple classification of FV charts. This classification links the characteristics seen on the FV charts with particular lower urinary tract dysfunctions. Whilst this classification gives a guide to the patient's possible diagnosis, the overlap between symptomatic groups and normal controls is large. FV charts have an important role in objectively, recording patients' symptoms, both as a base line and after therapeutic interventions. They are particularly important in everyday clinical use as a vital part of bladder training. In the research field they are important in providing objective evidence of changes in subjective symptoms in a treatment group as opposed to the placebo group. They have been particularly valuable in the evaluation of new drugs for the treatment of detrusor overactivity and benign prostatic obstruction. Most FV charts rely on pen and paper. However in the computer age the possibility of computerising the FV chart is attractive, but as yet not fully evaluated. At present it is advised that a simple frequency volume chart with the additional recording of incontinent episodes, pad usage and overall assessment of fluid intake is used for routine clinical use. In a research setting urinary diaries may add significant additional information, allowing a more complete evaluation of novel therapies.