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training and PHP enabled patients to treat themselves while using fewer resources. Patients in the PHP group were more enthusiastic, more confident, and had greater self-awareness than controls. Although patients in the PHP group were instructed to consult their general practitioner and admit themselves to hospital at an early stage of their exacerbation they reduced their demands on health services. This may be due to patients in the PHP group feeling in less need of help from others. This study shows that PHP can reduce consumption of health services after discharge from hospital. Since

Effect of

introducing PHP in our department we have also found a considerable shortening of the average length of in-hospital stay.33 REFERENCES 1. Tave DR. Minimization: a new method of assigning patients treatment and control groups. Clin Pharmacol Ther 1974; 15: 443-49. 2. Ringsberg KC, Wiklund I, Wilhelmsen L. Education of adult patients at an "asthma school": effects on quality of life, knowledge and need for nursing. Eur Respir J 1990; 3: 33-37. 3. Tougaard L, Anderson KD, Jung E, et al. Stuegang afskaffet. Ugeskr

Laeger 1991;153:1306-09.

presentation of partogram information on obstetric decision-making

The way in which medical information is presented may affect doctors’ decision-making. We have assessed whether changing the appearance of the same information on the partogram affects clinical decisions during labour. Sixteen junior obstetricians were asked about how they would manage six hypothetical cases of difficult labour. Information was given by partogram, in which we varied either the relative scales of the x and y axes or whether the latent phase of labour had been included. Doctors were more likely to intervene and to intervene more actively if the progress of labour curve appeared flat and if the latent phase was included. The shape and point of origin of the partogram probably influence intervention rates in practice and may partly explain the low rates of caesarean section in some hospitals.

Introduction

Graphic designers know that the way information is presented influences audience behaviour.1 For example, to exaggerate, say, a rising crime rate, a journalist merely has to choose a scale on a graph so that the crime rate curve rises more steeply, or the lower values from one axis can be omitted so that the percentage increase seems greater. Similar factors probably affect the interpretation of medical data and influence doctors’ decisions. Obstetricians have to decide whether and when to intervene during labour-ie, to accelerate it with oxytocics or by rupture of the membranes, or to deliver the baby by forceps or caesarean section. Opinions differ about the indications for these interventions, and obstetricians may disagree both among themselves and with their own earlier decisions.2 The increasing rate of intervention in labour both in the UK and in the USA is worrying, so any relevant factors that might influence whether an obstetrician intervenes during labour should be investigated. Labour progress is usually monitored with a partogram, which is a graph of cervical dilatation against time.33 Partograms vary with respect to the relation between the vertical scale (y axis) used for cervical dilatation and the horizontal scale (x axis) representing elapsed time in labour or since admission. Obstetric units also have different policies about when a partogram should be started. Possible

differences between partograms are shown in fig 1 in which that used in the National Maternity Hospital in Dublin (which has a very low caesarean rate) with a time (hours)-todilatation (cm) ratio (x/y) of 1/1is compared with two others (from anonymous hospitals) with 2/1 and 2-66/1 ratios. We set out to see whether either the gradient of the curve or inclusion of the latent phase on the partogram influenced doctors’ decision-making. We decided to test the hypothesis that doctors would be more likely to intervene when the scale of the partogram led to a flattened cervical dilatation curve or when the latent phase of labour was drawn on the partogram, since a flat partogram and a long latent phase would tend to point to impending labour or difficulty and the need for intervention.

Methods A convenience sample of sixteen junior obstetricians were asked how they would each manage a series of six hypothetical labours. In each case, labour progress was slow or there was some other factor (such as borderline evidence of fetal distress) that might prompt intervention, especially if labour was progressing slowly. All cases were selected so that difficult decisions were needed. Each doctor was presented with the details of each case twice in random order two months apart as follows:

before first interview.

They were not told about our hypothesis nor that they would see the same information presented in two different ways. In the two presentations of each case, the factual information including the cardiotocograph was the same but the format of presentation of the cervical dilatation information was varied. In the first three cases partograms with a steep format (x to y ratio of 1/1) and a shallow format (1-5/1) were used (fig 2a and 2b). In the last three cases partograms with and without an eight-hour latent phase of labour

University Department of Obstetrics and Gynaecology, St James’ Hospital, Leeds, UK (R. S. V. Cartmill, MRCOG, J. G. Thornton, MD). Correspondence to Mr J. G. Thornton, Institute of Epidemiology and Health Services Research, Leeds University, 34 Hyde Terrace, Leeds LS2 9LN, UK.

ADDRESSES:

1521

Duration of labour

Duration of labour

(h)

Fig 1-(A) Dublin partogram (x to partogram (x to y ratio 2 66/1).

y ratio

1/1); (B)

Duration of labour

(h)

anonymous partogram

(x

(of less than 3 cm dilatation) were used, but in the partogram in which the latent phase was omitted graphically (fig 3), it was recorded in writing with the other background information. The three cases for which inclusion of the latent phase was varied were all drawn on shallow-format partograms with an x to y ratio of 1 ’5/1. The junior doctors were asked to describe their management of each case. Their responses varied--eg, continued observation, repeated vaginal assessment, tests of fetal wellbeing needed, acceleration of labour with oxytocin, delivery by forceps, trial of

(h)

to y ratio

2/1); (C)

anonymous

forceps, or caesarean section. For each pair of cases the difference in the doctor’s responses was classified as (a) no difference between presentations, (b) more active intervention recommended as expected by the hypothesis, or (c) more active intervention in the opposite direction to that expected. Randomisation and concealment of the purpose of the study from the obstetricians was achieved by the preparation for each doctor of an envelope containing one complete set of the six cases before each first interview. Which of the six formats (three steep or shallow, three latent phase included or excluded) to use in the first interview was determined by six coin tosses. At the second interview the complementary formats were presented. The numbers of

cases

in which the first decision made

was

unchanged from the second decision was recorded. The statistical significance of any difference between the number changing in the direction predicted by the hypothesis, and those changing in the opposite direction, was measured with McNemar’s test for paired alternatives.

Results

Duration of labour

(h)

Fig 2-(A) Example case on steep (1/1)partogram; (B)same case on shallow (1 -5/1) partogram.

By serendipity, coin randomisation led to a near balance in the order of presentation of formats, with 24 of 48 pairs having the steep format presented first, and 21 of 48 the latent phase included first. Moreover, there was no trend for decisions to vary in response to the order of presentation. Of the 48 pairs of decisions made with steep or shallow formats, 18 were unchanged between the formats, 21 were changed in the direction expected by the hypothesis, and 9 in the opposite direction. Thus, 70% of the changes (21/30) were in the expected direction (0-05 >p> 0-01). These 21 decisions were to deliver by caesarean in 6 cases, to carry out instrumental vaginal delivery in 5, to start oxytocin in 8, and to measure fetal pH in 2. Of the 48 pairs of decisions made with. latent phase included or omitted, 29 were unchanged between the formats, 14 were changed in the expected direction, and 5 in the opposite direction. Thus, the proportion of changes in the expected direction was 14 out of 19 (74%) These 14 decisions were delivery by (0.l>p>0.05). caesarean in 8, to start oxytocin in 3, and to measure fetal pH in 3.

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These observations may partly explain the variation in section rates between units. Most UK units use partograms that portray progress of labour as a relatively flat line, and if the patient presents to the labour ward in the latent phase, staff draw this on the partogram. In the National Maternity Hospital, Dublin, which has a worldwide reputation for its low caesarean section rateasteep partogram is used and the junior doctors and midwives are taught to delay recording data on it until they are sure that labour is established. The latent phase is thus rarely drawn on the partogram. It is often claimed that the policy of active management of labour has kept the caesarean section rate low in this and similar units,4but such a rate may also be due to decisions made because of the shape of the partogram. Many units are developing computerised partograms: we believe that they should choose a steep shape similar to the Dublin partogram if they wish to reduce their caesarean section rate. The World Health Organisation has recommended a partogram with an x to y ratio of 1/1(fig 4). Our results support this recommendation; we further advise that the latent phase data should be omitted. caesarean

Duration of labour

with latent case with latent phase excluded.

Fig 3-(A) Example

case

(h)

phase included; (B)

Overall, 35 of 49 (71%) changes

REFERENCES same

1. Tufte ER. The visual

were

in the

expected

direction (p < 0-01).

Discussion Our findings indicate that doctors’ decision-making about slow labour is influenced by the way in which information is presented graphically. Doctors are less likely to intervene during labour if the cervical dilatation is drawn on a partogram with a low x to y ratio so that the progress line has a steep gradient than if the x to y ratio is higher so that the line is flatter. Moreover, if the latent phase of labour is drawn on the partogram labour seems longer with slow progress, and doctors are again more likely to intervene than if the information is omitted from the graph. Since the rate of progress is the same in both cases, the difference in decision-making must be due to a change in perception. The decisions that we assessed were hypothetical and we cannot be certain that the size of the effect would be the same in practice. Nonetheless the difference between the steep and flat versions of the partogram was modest compared with the variation seen in some hospital charts. We have seen partograms with x to y ratios of up to 266/1 in use (fig lc) and would expect there to be even greater intervention if we had measured the effect of using these. The resulting changes in management are also important--eg, in the present study, 14 caesarean sections out of 35 changed decisions.

Time (h)

Fig 4-World (1/1 ).

Health

Organisation recommended partogram

display of quantitative information. Cheshire, Connecticut: Graphics Press, 1983. 2. Barrett JFR, Jarvis GJ, MacDonald HN, Buchan PC, Tyrrell SN, Lilford RJ. Inconsistencies in clinical decisions in obstetrics. Lancet 1990; 336: 549-51. 3. Friedman EA. Labour: clinical evaluation and management, 2nd ed. New York: Appleton Century Crofts, 1978. 4. O’Driscoll D, Meagher D. Active management of labour. Philadelphia: Saunders, 1990.

From The Lancet Competitive dietaries The great Roman general, Corbulo, we are informed by Tacitus, in his Armenian campaign reduced to extremities, his army having suffered, not indeed from losses in battle, but from being driven to satisfy its hunger from the flesh of sheep. To the average Briton into whose dietetic cult the mutton chop enters so largely, this announcement must seem inexplicable; so much so that he might be excused for thinking lightly of the stamina or pluck of his forefathers who allowed themselves to be conquered by soldiery for whose stomachs the flesh of sheep was too strong. The fact is, however, as Tacitus has stated it; and we know from other authorities that animal food as a constant element in the Roman soldiers’ fare was found hurtful to his health and efficiency. Caesar, in his Gallic war, tells the same story: Ut complures dies milites frumento caruerint et pecore extremam famem sustentarent (how for several days his troops did without com-meal and sustained the extreme of hunger on mutton). Com-meal was the grand necessary of life to those legionaries who, led by Caesar, subdued the world, and who counted themselves starved, and were apt to mutiny if reduced to the "famine fare" of animal food. Even British troops have been known to suffer from an exclusive meat diet, as indeed we found to our cost in the Zulu campaign of 1879 ; while the preference of the Roman soldiery for vegetable food has its justification in the experience of the Russian army, and still more of the German one in 1870, which carried that memorable campaign to its triumphant close on the erbswurst (pea-sausage flavoured with a little bacon). Without for a moment lending countenance to the vegetarian who would cut off butcher’s meat from human consumption, we may concede to him that an animal diet, unbalanced by a due proportion of the "kindly fruits of the earth", is distinctly prejudicial to the consumer, particularly to the resident in cities, whose opportunities of open air exercise are few and far between. was

(April 16,1892)

Effect of presentation of partogram information on obstetric decision-making.

The way in which medical information is presented may affect doctors' decision-making. We have assessed whether changing the appearance of the same in...
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