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Personal stereos and hearing loss
along with a motherly admonition by the DOT nurse to return to school promptly. Shortly after the boys left, police entered the clinic seeking the boys’ identities and exit route. We learned later, the two youths and a third accomplice had been apprehended and arrested. It seems the patient and his friends even though deep in the midst of a crime spree, including the theft of a car, stopped in the clinic to get his DOPT. All providers of tuberculosis services should aim to advance tuberculosis treatment to the highest possible point in a patient’s motivation and consciousness. Our patient had reached that level, although unfortunately at his own peril. This example is evidence of committed patients to a committed programme. Judith Shain-Alvaro, Patricia Garcia, *Lee B Reichman Preventive Medicine, National Tuberculosis Center, New Jersey Medical School, Suite GB-1, University Heights, Newark, NJ 07107, USA 1
Weiss SE, Slocum PC, Blais FX, et al. The effect of directly observed therapy on the rates of resistance and relapse in tuberculosis. N Engl J Med 1994; 330: 1179–84. 2 Garner P. What makes DOT work? Lancet 1998; 352: 1326–27. 3 Zwarenstein M, Shoeman JH, Vundule C, Lombard CJ, Tatley M. Randomised controlled trial of self-supervised and directly observed treatment of tuberculosis. Lancet 1998; 352: 1340–43.
(among how many?) and Peto4 has shown that spurious associations can be found with this method. Moreover, recall bias is very likely to be present because adults with hearing loss may easily ascribe their loss to childhood ear infections; those with tinnitus (and associated hearing loss) might even use personal stereos as a masking device. Although these findings can be u s e d to generate many plausible hypotheses, they cannot be used to assess the causation of the hearing loss that was detected. Surely a more sensible recommendation from the data presented is to carry out a prospective study in young people with a confirmed history of ear infections in whom hearing levels are measured before and after regular use of personal stereos? Christopher Cates Manor View Practice, Bushey Health Centre, Bushey, W atford WD2 2NN, Hertfordshire, UK ( e-mail: [email protected]) 1
2
3
Personal stereos and hearing loss Sir—The conclusions of Agnès Job and colleagues (Jan 2, p 35) 1 go far beyond the data represented. They do not consider treatment of otitis media or give any evidence in support of the question that otitis in childhood can be cured or prevented in a way that affects later hearing problems. Job and colleagues seem to assume that such treatment exists and would protect the users against possible deafness associated with future use of personal stereos. In a systematic review, Glasziou and colleagues2 addressed the use of antibiotics in acute otitis media by looking at the results of randomised trials that compared antibiotics with placebo. They found that the use of antibiotics did not alter the hearing of children in the months after an infection. Similarly, a meta-analysis of trials of antibiotics in recurrent otitis media3 did not show a difference in long-term outcomes when antibiotic use was compared with placebo. Job and colleagues present one subgroup analysis of their data
756
4
Job A, Raynal M, Rondet P. Hearing loss and the use of personal stereos in young adults with antecedents of otitis media. Lancet 1999; 353: 35. Glasziou PP, Hayem M, Del Mar CB. Antibiotic versus placebo for acute otitis media in children (Cochrane Review). In: Cochrane Library (CDROM and online). Cochrane Collaboration; issue 4. Oxford: Update Software, 1998. Williams RL, Chalmers TC, Stange KC, Chalmers FT, Bowlin SJ. Use of antibiotics in preventing recurrent acute otitis media and in treating otitis media with effusion: a meta-analytic attempt to resolve the brouhaha. JAMA 1993; 270: 1344–51. Collins R, Gray R, Godwin J, Peto R. Avoidance of large biases and large random effects in the assessment of moderate treatment effects: the need for systematic overviews. Stat Med 1987; 6: 245–50.
Author’s reply Sir—We agree with most of Christopher Cates’ recommendations. It is obviously a good idea to repeat observations, to run prospective studies, and so on. With respect to possible recall bias: recall bias may result in an overestimation of the frequency of otitis in the group of people with hearing impairment, but such bias should apply to personal stereo users as well as to non-users. Cates’ view is that there is no effective treatment to prevent or cure otitis. We understand his point, but hope that he will agree with us that, while waiting for supplementary data, it is very reasonable to warn young adults with a history of otitis that the frequent use of personal stereos might be harmful. Agnès Job CRSSA, Unité de Psychologie, BP 87, 38702 La Tronche, France
Thromboprophylaxis for atrial fibrillation Sir—In his Jan 2 commentary on thromboprophylaxis for atrial fibrillation, Gregory Yip1 suggests that such patients should be stratified according to the annual risk of stroke; an opinion with which few would disagree. However, the absolute benefit depends also on the risk of severe haemorrhage. As a Cochrane review of the trials concludes “the margin between benefit and harm for warfarin prophylaxis in patients with chronic non-valvular atrial fibrillation is uncomfortably thin. The low absolute risk reductions observed in trials would likely be overwhelmed in less controlled settings by problems associated with the use of warfarin.”2 Estimates of the risk of serious and fatal haemorrhage vary substantially. Levine and colleagues3 estimate the annual risk of fatal haemorrhage is between 0% and 4·8%. No data exists for the haemorrhagic risk in routine UK practice. Recent work4 suggests patients can be stratified for the risk of major bleeding with just four risk factors: age, history of gastrointestinal bleeding, history of stroke, and other comorbidity. Low-risk patients have a risk of severe haemorrhage of 3% per year, whereas high-risk patients have a risk of 43% per year.4 Many UK anticoagulant clinics are computerised which could facilitate collection of data for prospective cohort studies. These studies could establish absolute risks of bleeding, confirm the possibility of risk stratification, and identify whether measures such as vigorous avoidance of over anticoagulation can reduce the incidence of bleeds in high-risk populations. Users and developers of computer programs for the administration of anticoagulant control should agree common standards to permit data pooling and comparison. R G Dalton Department of Haematology, Cheltenham General Hospital, Cheltenham GL52 6RX, UK (e-mail: [email protected]) 1
Yip GYH. Thromboprophylaxis for atrial fibrillation. Lancet 1999; 353: 4–6. 2 Database no DARE-950385 of the database of abstracts of reviews of effectiveness. In: Cochrane Library (CDROM and online). Cochrane Collaboration; issue 4. Oxford: Update Software, 1998. 3 Levine MN, Hirsh J, Landefeld S, Raskob G. Hemorrhagic complications of anticoagulant therapy. Chest 1992; 102 (suppl): 352–63. 4 Beyth RJ, Quinn LM, Landefield CS. Prospective evaluation of an index for predicting the risk of major bleeding in outpatients treated with warfarin. Am J Med 1998; 105: 91–99.
THE LANCET • Vol 353 • February 27, 1999
Weiss SE, Slocum PC, Blais FX, et al. The effect of directly observed therapy on the rates of resistance and relapse in tuberculosis. N Engl J Med 1994; 330: 1179–84. 2 Garner P. What makes DOT work? Lancet 1998; 352: 1326–27. 3 Zwarenstein M, Shoeman JH, Vundule C, Lombard CJ, Tatley M. Randomised controlled trial of self-supervised and directly observed treatment of tuberculosis. Lancet 1998; 352: 1340–43.
(among how many?) and Peto4 has shown that spurious associations can be found with this method. Moreover, recall bias is very likely to be present because adults with hearing loss may easily ascribe their loss to childhood ear infections; those with tinnitus (and associated hearing loss) might even use personal stereos as a masking device. Although these findings can be u s e d to generate many plausible hypotheses, they cannot be used to assess the causation of the hearing loss that was detected. Surely a more sensible recommendation from the data presented is to carry out a prospective study in young people with a confirmed history of ear infections in whom hearing levels are measured before and after regular use of personal stereos? Christopher Cates Manor View Practice, Bushey Health Centre, Bushey, W atford WD2 2NN, Hertfordshire, UK ( e-mail: [email protected]) 1
2
3
Personal stereos and hearing loss Sir—The conclusions of Agnès Job and colleagues (Jan 2, p 35) 1 go far beyond the data represented. They do not consider treatment of otitis media or give any evidence in support of the question that otitis in childhood can be cured or prevented in a way that affects later hearing problems. Job and colleagues seem to assume that such treatment exists and would protect the users against possible deafness associated with future use of personal stereos. In a systematic review, Glasziou and colleagues2 addressed the use of antibiotics in acute otitis media by looking at the results of randomised trials that compared antibiotics with placebo. They found that the use of antibiotics did not alter the hearing of children in the months after an infection. Similarly, a meta-analysis of trials of antibiotics in recurrent otitis media3 did not show a difference in long-term outcomes when antibiotic use was compared with placebo. Job and colleagues present one subgroup analysis of their data
756
4
Job A, Raynal M, Rondet P. Hearing loss and the use of personal stereos in young adults with antecedents of otitis media. Lancet 1999; 353: 35. Glasziou PP, Hayem M, Del Mar CB. Antibiotic versus placebo for acute otitis media in children (Cochrane Review). In: Cochrane Library (CDROM and online). Cochrane Collaboration; issue 4. Oxford: Update Software, 1998. Williams RL, Chalmers TC, Stange KC, Chalmers FT, Bowlin SJ. Use of antibiotics in preventing recurrent acute otitis media and in treating otitis media with effusion: a meta-analytic attempt to resolve the brouhaha. JAMA 1993; 270: 1344–51. Collins R, Gray R, Godwin J, Peto R. Avoidance of large biases and large random effects in the assessment of moderate treatment effects: the need for systematic overviews. Stat Med 1987; 6: 245–50.
Author’s reply Sir—We agree with most of Christopher Cates’ recommendations. It is obviously a good idea to repeat observations, to run prospective studies, and so on. With respect to possible recall bias: recall bias may result in an overestimation of the frequency of otitis in the group of people with hearing impairment, but such bias should apply to personal stereo users as well as to non-users. Cates’ view is that there is no effective treatment to prevent or cure otitis. We understand his point, but hope that he will agree with us that, while waiting for supplementary data, it is very reasonable to warn young adults with a history of otitis that the frequent use of personal stereos might be harmful. Agnès Job CRSSA, Unité de Psychologie, BP 87, 38702 La Tronche, France
Thromboprophylaxis for atrial fibrillation Sir—In his Jan 2 commentary on thromboprophylaxis for atrial fibrillation, Gregory Yip1 suggests that such patients should be stratified according to the annual risk of stroke; an opinion with which few would disagree. However, the absolute benefit depends also on the risk of severe haemorrhage. As a Cochrane review of the trials concludes “the margin between benefit and harm for warfarin prophylaxis in patients with chronic non-valvular atrial fibrillation is uncomfortably thin. The low absolute risk reductions observed in trials would likely be overwhelmed in less controlled settings by problems associated with the use of warfarin.”2 Estimates of the risk of serious and fatal haemorrhage vary substantially. Levine and colleagues3 estimate the annual risk of fatal haemorrhage is between 0% and 4·8%. No data exists for the haemorrhagic risk in routine UK practice. Recent work4 suggests patients can be stratified for the risk of major bleeding with just four risk factors: age, history of gastrointestinal bleeding, history of stroke, and other comorbidity. Low-risk patients have a risk of severe haemorrhage of 3% per year, whereas high-risk patients have a risk of 43% per year.4 Many UK anticoagulant clinics are computerised which could facilitate collection of data for prospective cohort studies. These studies could establish absolute risks of bleeding, confirm the possibility of risk stratification, and identify whether measures such as vigorous avoidance of over anticoagulation can reduce the incidence of bleeds in high-risk populations. Users and developers of computer programs for the administration of anticoagulant control should agree common standards to permit data pooling and comparison. R G Dalton Department of Haematology, Cheltenham General Hospital, Cheltenham GL52 6RX, UK (e-mail: [email protected]) 1
Yip GYH. Thromboprophylaxis for atrial fibrillation. Lancet 1999; 353: 4–6. 2 Database no DARE-950385 of the database of abstracts of reviews of effectiveness. In: Cochrane Library (CDROM and online). Cochrane Collaboration; issue 4. Oxford: Update Software, 1998. 3 Levine MN, Hirsh J, Landefeld S, Raskob G. Hemorrhagic complications of anticoagulant therapy. Chest 1992; 102 (suppl): 352–63. 4 Beyth RJ, Quinn LM, Landefield CS. Prospective evaluation of an index for predicting the risk of major bleeding in outpatients treated with warfarin. Am J Med 1998; 105: 91–99.
THE LANCET • Vol 353 • February 27, 1999