Meta-analysis: excess mortality after hip fracture among older women and men

Abstract

Background: Although an increased risk for death after hip fracture is well established, whether this excess mortality persists over time is unclear.

Purpose: To determine the magnitude and duration of excess mortality after hip fracture in older men and women.

Data sources: Electronic search of MEDLINE and EMBASE for English and non-English articles from 1957 to May 2009 and manual search of article references.

Study selection: Prospective cohort studies were selected by 2 independent reviewers. The studies had to assess mortality in women (22 cohorts) or men (17 cohorts) aged 50 years or older with hip fracture, carry out a life-table analysis, and display the survival curves of the hip fracture group and age- and sex-matched control groups.

Data extraction: Survival curve data and items relevant to study validity and generalizability were independently extracted by 2 reviewers.

Data synthesis: Time-to-event meta-analyses showed that the relative hazard for all-cause mortality in the first 3 months after hip fracture was 5.75 (95% CI, 4.94 to 6.67) in women and 7.95 (CI, 6.13 to 10.30) in men. Relative hazards decreased substantially over time but did not return to rates seen in age- and sex-matched control groups. Through use of life-table methods, investigators estimated that white women having a hip fracture at age 80 years have excess annual mortality compared with white women of the same age without a fracture of 8%, 11%, 18%, and 22% at 1, 2, 5, and 10 years after injury, respectively. Men with a hip fracture at age 80 years have excess annual mortality of 18%, 22%, 26%, and 20% at 1, 2, 5, and 10 years after injury, respectively.

Limitations: Cohort studies varied, sometimes markedly, in size, duration of observation, selection of control populations, ascertainment of death, and adjustment for comorbid conditions. Only published data that displayed findings with survival curves were examined. Publication bias was possible.

Conclusion: Older adults have a 5- to 8-fold increased risk for all-cause mortality during the first 3 months after hip fracture. Excess annual mortality persists over time for both women and men, but at any given age, excess annual mortality after hip fracture is higher in men than in women.

Primary funding source: Fund for Scientific Research and Willy Gepts Foundation, Universitair Ziekenhuis Brussel.

Appendix Figure 1. Literature search and selection

Adapted from MOOSE Statement flow diagram (33). * These 24 articles present survival curves for 22 and 17 unique cohorts of women and men with hip fracture, respectively, as well as age- and sex-matched control groups.

Appendix Figure 2. Meta-regression analyses exploring heterogeneity of the cumulative RHs for short-term (1-year) all-cause mortality in older women and men, according to maximum duration of study

The square represents the Dubbo Osteoporosis Epidemiology Study, which was done in Australia and had a 15-year observation period (66). The authors acknowledge that there was probably selection bias in their study because participants were healthier than nonparticipants (67). RH = relative hazard.

Appendix Figure 3. Meta-regression analyses exploring heterogeneity of the cumulative RHs for short-term (1-year) all-cause mortality in older women and men, according to average probability of death after 1 year

The square represents the Dubbo Osteoporosis Epidemiology Study, which was done in Australia and had a 15-year observation period (66). The authors acknowledge that there was probably selection bias in their study because participants were healthier than nonparticipants (67). RH = relative hazard.

Figure 1. Forest plots of long-term (10-year) all-cause mortality in older women and men

Squares represent the long-term (10-year) cumulative relative hazard for all-cause mortality according to sex. Horizontal lines indicate 95% CIs. The dotted vertical line is the pooled relative hazard; the solid vertical line is the null effect. The size of the squares is proportional to the weight of the studies.

Figure 2. Forest plots of short-term (1-year) all-cause mortality in older women and men

Squares represent the short-term (1-year) cumulative relative hazard for all-cause mortality according to sex. Horizontal lines indicate 95% CIs. The dotted vertical line is the pooled relative hazard; the solid vertical line is the null effect. The size of the squares is proportional to the weight of the studies.

Figure 3. Relative hazard of all-cause mortality for women and men with hip fracture versus control groups during a given follow-up period starting at the time of injury

Solid circles represent the pooled relative hazard. Vertical bars represent the corresponding 95% CIs. The dotted horizontal line is the null effect.

Figure 4. Differences in absolute risk for death (excess mortality) from all causes for women and men with hip fracture compared with control participants during a given follow-up period starting at the time of injury