Numbers of admissions and procedures
There were 151 trusts with at least 100 admissions for hip fracture, yielding 129 522 admissions in patients aged ≥ 65 during the three years. A total of 18 508 died in hospital (14.3%), of whom 2068 (11.2%) died in another NHS hospital after transfer. Another 7428 admissions were excluded because of invalid data (mainly duplicate records and invalid dates of admission or discharge).
Overall, only 9206 (7.1%) had no procedure recorded (), ranging from 0.8% to 23.2% between trusts. The mean number of fixation and replacement procedures was 761 per trust (range 80-1854). The proportion waiting more than one day or more than two days varied more than twofold between trusts.
Basic figures (for all three years combined) for 2001-2 to 2003-4 for all NHS hospitals in England
Comorbidity was more common in surgical patients with delay compared with those with at most one day's delay and those managed medically (). The differences in proportions across the delay groups in were highly significant for each variable (P < 0.001, except P = 0.081 for hypertension, Cochran-Armitage tests for trend).
Frequency of comorbidity variables with respect to presence and timing of surgery. Figures are numbers (percentages) of patients
Factors associated with mortality and emergency readmission
gives odds ratios for mortality in hospital and emergency readmission for each factor considered. Age, sex, and fifth of deprivation were highly significant (P < 0.001, Wald tests) for all outcomes, and comorbidity factors were usually significant.
Odds ratios (95% confidence intervals) for death and readmission for age, sex, deprivation fifth, and comorbidity
The most common single cause (primary diagnosis) of emergency readmission within 28 days was hip fracture (11.9% for all patients and 10.2% for those having either a fixation or replacement), followed by “complications of internal prosthetic devices, implants and grafts” (ICD-10 T84, 7.2%) and unspecified pneumonia (J18, 5.5%). The data do not allow us to distinguish between new and existing fractures.
Effect of type of surgery and operative delay
Fixation and replacement procedures had similar mortality and readmission rates; patients with some other operation had almost twice the death rate and those with no operation had the highest rate of all. For patients having either a fixation or replacement, 11.0% of readmissions were for “complications of surgical and medical care not elsewhere classified” (codes T80-T88). These were more common after a replacement (14.5% v 8.1%, P < 0.001, χ2 test).
Overall, 39.9% of procedures were performed more than one day after admission (range between trusts 1.1%-82.7%) and 21.3% were delayed more than two days (1.1%-62.4%). Delay rates were similar for the two main procedure types but slightly more common in the oldest patients (35.9% in the 65-69 age range had more than one day's delay compared with 40.3% in those aged ≥ 95).
Variables associated with higher rates of delay were older age, female, the four most deprived fifths, replacement procedure, and each comorbidity variable (). For patients having only either a fixation or a replacement procedure and death or 30 day death as the outcome, age, sex, and fifth of deprivation were again highly significant, as was operative delay (both categories) and the comorbidity variables (P < 0.001, Wald tests). For readmissions, there was little evidence of an effect of delay (odds ratio 1.04, P = 0.13, for more than one day's delay and 1.04, P = 0.15, for more than two days' delay) ().
Odds ratios (95% confidence interval) for death and readmission by intervention, adjusted for age, sex, deprivation fifth, and comorbidity
Adjustment for comorbidity reduced the estimated effect of delay. For all deaths in hospital, the odds ratio for more than one day's delay fell from 1.39 (95% confidence interval 1.34 to 1.44) to 1.27 (1.23 to 1.32) and that for more than two days' delay fell from 1.60 (1.54 to 1.67) to 1.43 (1.37 to 1.49) after adjustment for secondary diagnoses; the impact of adjustment was less for emergency readmissions.
After adjustment for all measured factors, the death rate increased with delay in operation, as shown by the adjusted odds ratios relative to at most one day's delay in . There seems to be a decline after 12 days, which is probably due to some selection bias operating whereby more of the most ill patients had died before they could have an operation.
Odds ratios of death within hospital by operative delay relative to at most one day's delay, after adjustment for age, sex, deprivation, type of procedure (fixation and replacement only), and selected comorbidities
Difference between observed and expected deaths
We estimated differences between the observed number of deaths and the number expected with at most one day's delay for each trust. For a delay of more than one day, the sum of the differences in the three years was 1155 (944 to 1366) for more than one day's delay and 825 (752 to 898) for more than two days' delay. Differences per year at trust level ranged from 10 fewer to 23 more deaths for more than one day's delay.
At trust level, there were no significant relations overall between delay rates and (in turn) the proportion of patients managed medically (P = 0.493), mortality (P = 0.207), and the readmission rate (P = 0.127). The 37 out of 151 trusts with more than half of their patients waiting more than one day for a fixation or replacement procedure, however, had significantly greater mean observed minus expected deaths than the other 114 (10.3, 0.8 to 19.8), after adjustment for volume by dividing the observed minus expected by the number of admissions and multiplying by 1000 to give a “difference per 1000 admissions.” The trust with the largest difference (either raw or volume adjusted) had the second highest mortality and the 19th highest rate of delay. shows the differences per 1000 admissions by trust for the three years combined.
Mean annual difference between observed and expected deaths in hospital per 1000 admissions by trust associated with an operative delay of more than one day