Subjects, methods, and results

The episode (described in detail in accompanying article3) depicted a man suffering potentially fatal liver damage after an untreated paracetamol overdose. Although the particular dose (50 tablets) and delay before presentation (2 days) were mentioned, the episode did not specify minimal toxic doses or maximum safe delays.

At one week and 32 weeks after this episode was broadcast, we sent questionnaires to members of the BBC Television Opinion Panel. Panel members are recruited by structured sampling to be representative of the adult UK population and are sent weekly questionnaires related to their viewing. At one week after the broadcast, we asked them whether they had viewed the relevant Casualtyepisode and questions to test their knowledge of the delayed hepatotoxic effects of paracetamol in overdose, maximum safe delays before seeking help, and fatal doses of several drugs commonly used for self poisoning (see table). The test questions were repeated at 32 weeks after thebroadcast, together with further questions about members' interest in medical matters and viewing of other medical dramas and documentaries. General medical knowledge was tested by two multiple choice questions: “What is a crash team?” and “What is a laparotomy?” Responses from the two surveys were linked. At one week, 2792 out of 3115 panel members participated, 1030 (37%) of whom reported watching the episode. At 32 weeks, 1282 of these participants remained in the panel, of whom 475 (37%) had seen the episode.

Non-viewers were more likely not to respond or respond “don't know” to all questions in both surveys. At one week, significantly more viewers (85%) than non-viewers (45%) correctly identified paracetamol as having hepatotoxic effects. By 32 weeks, this knowledge had declined by 12% in viewers (P<0.0005) and increased by 5% in non-viewers (P=0.004). The effects were little changed by using a logistic regression model to adjust for demographic factors and measures of medical interest, knowledge, and viewing habits.

Viewers indicated longer minimal safe delays before seeking help than non-viewers, the differences being small but significant. There was no difference between viewers and non-viewers in lethal doses of paracetamol or the ranking of paracetamol toxicity compared with that of other drugs.

Comment

Rates of deliberate self harm continue to increase: overdose is the most common method, and paracetamol the most commonly used substance.1 Baseline knowledge in this study was high: 45% of those who did not see the episode knew of the delayed hepatotoxicity of paracetamol, possibly reflecting recent extensive media attention.

Television is an important potential source of medical information,4 with programmes such as Casualty attracting audiences of over 10 million. Our study showed that viewers of a Casualtyepisode registered and retained information about paracetamol toxicity presented in the programme among other distracting story lines. Interestingly, it also revealed that the knowledge obtained was strictly restricted to the presented facts and that incomplete messages might have been misinterpreted. There was also an increase in overdose presentations to general hospitals after the broadcast.3 Medical messages broadcast within television programmes are likely to have an impact on the knowledge of the general public: editors should be aware of this and ensure that they are accurate and complete.