In relation to this report by Chu et al.[1] we would like to share both our experience and concerns about chronic ketamine use and urinary tract pathology. In the South West of England we have become aware of an increasing number of patients referred to urological services with complications of chronic ketamine use [2]. It is apparent that this is not only a problem in Hong Kong, but also in mainland Europe, Canada and Malaysia (personal communication) [3,4]. A recent British case report has brought such cases to the attention of UK urologists [5].

The features of the cases in the South West are comparable to those in the series from Hong Kong, i.e. severe dysuria, haematuria, urgency and frequency. Cystoscopy revealed small-volume erythematous bladders, and biopsy showed haemorrhagic cystitis with denuded epithelium. Severe complications include intractable symptoms (necessitating cystectomy and neobladder formation for symptomatic relief), renal impairment and hydronephrosis. Urgency and dysuria might be relieved to some degree by catheterization.

As increasingly many similar cases were referred to local urologists, it was clear that such ketamine-associated pathology was becoming a serious concern in the region. Ketamine use has been increasing with time. In 2006 ketamine was made a Class C substance via the Misuse of Drugs Act, and in 2007, 0.8% of individuals aged 16–24 were reported as using ketamine in the last year [5]. Amongst those involved in the UK ‘dance scene’ the lifetime prevalence of ketamine use is 42% and has been increasing at ⊕50% per year over the 5-year period from 1999 to 2003 [6,7], alarmingly amongst younger female ketamine users in the local area.

We have been working closely with the Bristol Drug Project, not only to ascertain the scale of the problem in the Bristol area, but to develop harm-reduction strategies and increase awareness amongst GPs, ketamine users and drug workers. To date, ⊕85 professionals and 30 heavy users of ketamine have attended workshops. A harm-reduction and detoxification regimen have been developed [8]. Of the 30 ketamine users, half have had urinary symptoms, most consulting their GPs and only two being referred for further investigation. This emerging problem appears to be widespread in the UK. We conducted an email survey of all current BAUS members; despite a response rate of 6.8%, 24 members described similar cases.

Whilst the course of the disease in not clear, from our experience and that of BAUS members, in about a third of cases the condition resolves, a third progress and a third remain stable after stopping ketamine use. It is important therefore that a multidisciplinary approach should be taken when managing these patients. Clearly stopping ketamine use is important and therefore specialist drug-support groups are appropriate. Increased awareness amongst GPs and urological surgeons is important.