Findings, comparison with other studies and interpretation
To our knowledge, this is one of the first studies comparing hospitalizations of nursing home residents and associated factors by sex. We found that male nursing home residents were 1.35-fold more often hospitalized during the preceding 12 months than females and that there seem to be differences in factors associated with hospitalizations between males and females. The chance of being hospitalized increased with decreasing age, increasing care dependency as well as increasing number of medications only in females. In males, these clear trends were not found and there were differences between sexes on the influence of length of stay and hospitalizations.
The literature indicates that hospitalizations of nursing home residents are relatively common but estimates vary widely across studies [
3,
18]. Besides different geographic areas and types of nursing homes or hospitalizations, the published studies use a wide range of measures, time periods and populations, making comparisons difficult. Hospitalizations are highest for persons before and shortly after being newly admitted to nursing homes and decline with length of stay [
3,
11,
29,
30]. This was also observed in our study, where persons institutionalized within the last 6 months were more often hospitalized during the preceding 12 months than residents with a longer length of stay. When compared to studies also including prevalent nursing home residents [
3,
14,
18,
31,
32], the proportion with one or more hospitalizations is much higher in our study than those reported from other western countries. These comparably high hospitalization rates in Germany have already been pointed out by Ramroth et al. [
11] in an earlier study using data that are now 15 years old.
Although not statistically significant in our study, the finding that male nursing home residents are more often hospitalized than females is consistent with the existing literature [
3,
10‐
14,
18]. However, in our systematic review [
18] we only found one study that reported further analyses stratified by sex and age [
10] and no study systematically assessed reasons for these differences or compared predictors of hospitalizations in multivariate analyses between sexes. However, understanding such sex-dependent patterns is a prerequisite to assess whether oversupply or undersupply might exist and to optimise care, but data on care needs, chronic medical conditions and service utilization in nursing home residents are often presented in aggregate for both sexes [
16].
Our most striking finding was that age had a quite different influence between sexes. Ronald et al., as the only study we found that presented hospitalization rates by age groups and sex, also revealed some differences [
10]. In females, they found a decrease in hospitalizations with increasing age, which is in line with our findings. Their results show only small differences between age groups in males. Although many studies adjust for sex in multivariate analyses [
14,
18,
29,
33], these results are largely influenced by the fact that about three quarters of nursing home residents are females. While it seems to be established that healthier nursing home residents are less frequently admitted to hospitals [
3,
33], we also found striking sex differences and this association was only seen in female residents. We used the level of care dependency and the number of scheduled medication as proxies for health status. For the quartiles of scheduled medications, which might be a better proxy for morbidity, we also found a clear trend that an increased number goes in line with an increased proportion of residents being hospitalized in females. When studying levels of care dependency, which reflect physical disabilities, this trend was weaker but, again, only shown in females. This phenomenon should be studied further in order to understand sex differences in hospitalizations of nursing home residents.
Strengths and limitations
Major strength of our study was that we were able to collect data of all residents living in the participating care units including their medication plans. Data were captured by the respective nursing staff and many health related information could be obtained from the residents’ records. However, some limitations have to be considered. First, we only included nursing homes in the northwestern part of Germany that were willing to participate, which might result in a selection bias and may impact the external validity of our findings. However, we tried to consider a heterogeneous sample of nursing homes including different sizes, providers and rural as well as urban regions. Second, although nursing staff should assess information on hospitalization from the residents’ records, a recall bias might be a further limitation in residents which were newly institutionalized or for which no data were available for other reasons. Besides whether residents were hospitalized at least once during the preceding 12 months, no further data on hospitalizations were assessed. Therefore, we do not have information on the number of hospitalizations, discharge diagnoses as well as length of hospital stay because we aimed to keep the burden of documentation as low as possible. Furthermore, for about one quarter (26.1%) length of stay was less than 12 months and some of their hospitalisations might have occurred before nursing home admission. Although there were missing values, data on hospitalization were missing for less than 5% of residents, which was quite small. We used a cross-sectional design and it was not possible to assess whether chronic conditions or changes in health status occur after hospital stay. However, our main objective was to investigate age and sex differences and these factors are not affected by hospitalization. Finally, our study is hampered by the small sample size, especially for males. The large confidence intervals indicate less accurate estimates and our results must be interpreted with some caution. However, especially the different trends between sexes are unlikely to be due to chance.