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The Pharmaceutical Journal Vol 265 No 7114 September 16, 2000
Pharmacy Practice Research
Papers presented at the British Pharmaceutical Conference, Birmingham, September 10 to 13, 2000 pR9

Laxative prescribing in primary care: age, gender and product analysis

By A. Offia*&134; , B. Veitch* and R. Walker*&134;

Introduction The prevalence of constipation has been shown to increase in the elderly and affect females more than males.1-3 However, it is unclear whether this pattern exists across all age groups and if this influences the products prescribed. This study was therefore undertaken to investigate, in primary care, the prescribing of laxatives in all age groups by gender and product.

Method Prescribing data for the 25 to 36 general medical practices participating in the Welsh general practice morbidity database (GPMD) from 1993 to 1998 were interrogated. Prescribed drugs were searched by brand name, generic name or Read code and linked to patient and clinical details. The outcome list was imported into SPSS 7.5 for analysis.
Laxatives were grouped according to their BNF classification and patient age was analysed in 10-year age bands. Items prescribed were standardised per 1,000 males or females per year in each age decile.

Focal points

  • The prevalence of constipation is reported to increase with age and be greater in females than males.
  • It is therefore expected that females receive more laxatives than males.
  • A prescribing database for more than 500,000 patients was interrogated to examine prescribing patterns by age, gender and product.
  • Elderly females in primary care do not receive significantly more laxatives than elderly males when adjusted for the greater number of females.

Result The records of 503,729 patients were searched over the six-year study period. A laxative item was prescribed on 167,594 occasions for a total of 30,907 individuals.
The majority of these individuals (21,362) only received one item. Patients aged 70-79, 80-89 and 60-69 years received the highest number of prescribed laxatives and accounted for 47,601 (28 per cent), 45,077 (27 per cent) and 23,547 (14 per cent) items, respectively. Although females accounted for 19,975 (65 per cent) of the patients who received a laxative and 109,761 (65 per cent) of all items prescribed, when the data was standardised per 1,000 females or males per year in each age decile the results presented in Figure 1 were obtained.
Osmotics accounted for 69,268 (41 per cent) of laxative items prescribed followed by stimulants (48,811 items; 29 per cent) and bulk forming agents (48,668 items; 29 per cent). Females accounted for 64 per cent, 61 per cent and 68 per cent of osmotic, stimulant and bulk-forming laxative items, respectively.
Osmotics were the most prescribed laxative group in all age bands except in those aged 40-49, 50-59 and 60-69 years, where bulk-forming laxatives were more frequently prescribed.

Figure 1
Figure 1. Laxative items per 1,000 males or females per year in each age decile from 1993 to 1998

Discussion This study has demonstrated that the number of laxative items prescribed increases with patient age, with more items being for females than for males. While this is consistent with the findings of others3 and the reported prevalence of constipation, the GPMD permitted the results to be corrected for the greater proportion of females in the older age group. The results so obtained then challenge conventional wisdom that elderly females receive significantly more laxatives than males. This needs to be investigated further, along with the rationale for the high use of osmotic laxatives in all age groups which is contrary to current prescribing advice.4
The Welsh GPMD has been little used for pharmacoepidemiological studies of the nature described. However, it would appear to be a rich source of information for those wishing to link prescribing data with clinical records to further understand and explain prescribing patterns.

*Welsh school of pharmacy, Cardiff university; &134;Gwent health authority, Pontypool.

References

1. Harari D, Gurwitz JH, Avorn J, Bohn R, Minaker KL. Bowel habit in relation to age and gender. Findings from National Health Survey and clinical implications. Arch Intern Med 1996; 156:315-20.
2. Talley NJ, O'Keefe EA, Zinsmeister AR, Melton LJ. Prevalence of gastrointestinal symptoms in elderly: a population-based study. Gastroenterology 1992; 102:895-901.
3. Stewart BS, Moore MT, Marks RG, Hale WE. Correlates of constipation in an ambulatory elderly population. Am J Gastroenterol 1992;87:859-64.
4. National Prescribing Centre. The management of constipation. MeReC Bulletin 1999;10:33-36.